[llvm] Reland [NFC] Move DroppedVariableStats to its own file and redesign it to be extensible. (PR #117042)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-cmake-x86_64-avx512-linux` running on `avx512-intel64` while building `llvm` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/133/builds/7786

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Profile-i386 :: Linux/corrupted-profile.c' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 1: rm -f /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
+ rm -f /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
RUN: at line 2: touch /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
+ touch /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
RUN: at line 3: /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/./bin/clang   -m32  -ldl  -fprofile-instr-generate -o /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/llvm/compiler-rt/test/profile/Linux/corrupted-profile.c
+ /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/./bin/clang -m32 -ldl -fprofile-instr-generate -o /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/llvm/compiler-rt/test/profile/Linux/corrupted-profile.c
/localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/llvm/compiler-rt/test/profile/Linux/corrupted-profile.c:64:12: warning: passing 'const IntPtrT *' (aka 'void *const *') to parameter of type 'void *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
   64 |     memset(&SrcDataStart->CounterPtr, 0xAB, sizeof(SrcDataStart->CounterPtr));
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/string.h:61:28: note: passing argument to parameter '__s' here
   61 | extern void *memset (void *__s, int __c, size_t __n) __THROW __nonnull ((1));
      |                            ^
1 warning generated.
RUN: at line 4: /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
+ /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
RUN: at line 5: /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw modifyfile
+ /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw modifyfile
RUN: at line 6: cp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw.old
+ cp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw.old
RUN: at line 7: /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw 2>&1 | FileCheck /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/llvm/compiler-rt/test/profile/Linux/corrupted-profile.c
+ /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/stage1/runtimes/runtimes-bins/compiler-rt/test/profile/Profile-i386/Linux/Output/corrupted-profile.c.tmp.profraw
+ FileCheck /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/llvm/compiler-rt/test/profile/Linux/corrupted-profile.c
FileCheck error: '<stdin>' is empty.
FileCheck command line:  FileCheck /localdisk2/buildbot/llvm-worker/clang-cmake-x86_64-avx512-linux/llvm/compiler-rt/test/profile/Linux/corrupted-profile.c

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/117042