[llvm] [NFC][ADT] Add RadixTree (PR #164524)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-s390x-linux-lnt` running on `systemz-1` while building `llvm` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/136/builds/5721

<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 'libFuzzer-s390x-default-Linux :: fuzzer-timeout.test' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/./bin/clang    -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta   --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/lib/fuzzer  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest # RUN: at line 1
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/./bin/clang -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/lib/fuzzer /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest
/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/./bin/clang    -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta   --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/lib/fuzzer  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutEmptyTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutEmptyTest # RUN: at line 2
+ /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/./bin/clang -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta --driver-mode=g++ -O2 -gline-tables-only -fsanitize=address,fuzzer -I/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/lib/fuzzer /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/TimeoutEmptyTest.cpp -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutEmptyTest
not  /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1 2>&1 | FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test --check-prefix=TimeoutTest # RUN: at line 3
+ not /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/stage1/runtimes/runtimes-bins/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/fuzzer-timeout.test.tmp-TimeoutTest -timeout=1
+ FileCheck /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test --check-prefix=TimeoutTest
/home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test:7:14: error: TimeoutTest: expected string not found in input
TimeoutTest: #0
             ^
<stdin>:28:44: note: scanning from here
==1640226== ERROR: libFuzzer: timeout after 1 seconds
                                           ^
<stdin>:33:104: note: possible intended match here
AddressSanitizer: CHECK failed: asan_report.cpp:227 "((current_error_.kind)) == ((kErrorKindInvalid))" (0x1, 0x0) (tid=1640226)
                                                                                                       ^

Input file: <stdin>
Check file: /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/llvm/compiler-rt/test/fuzzer/fuzzer-timeout.test

-dump-input=help explains the following input dump.

Input was:
<<<<<<
           .
           .
           .
          23: MS: 2 PersAutoDict-InsertByte- DE: "\000\000\000\000\000\000\000\001"-; base unit: 53878d54e17ec695415ba07300b98682dcd71070 
          24: 0x48,0x69,0x21,0x3f,0x69,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x1,0x69,0x69, 
          25: Hi!?i\000\000\000\000\000\000\000\001ii 
          26: artifact_prefix='./'; Test unit written to ./timeout-e0d16b09a6c904023b0979883c4743cc1aecfd87 
          27: Base64: SGkhP2kAAAAAAAAAAWlp 
          28: ==1640226== ERROR: libFuzzer: timeout after 1 seconds 
check:7'0                                                X~~~~~~~~~~ error: no match found
          29: AddressSanitizer:DEADLYSIGNAL 
check:7'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          30: ================================================================= 
check:7'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          31: AddressSanitizer:DEADLYSIGNAL 
check:7'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          32: ================================================================= 
check:7'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          33: AddressSanitizer: CHECK failed: asan_report.cpp:227 "((current_error_.kind)) == ((kErrorKindInvalid))" (0x1, 0x0) (tid=1640226) 
check:7'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
check:7'1                                                                                                            ?                         possible intended match
...

```

</details>

https://github.com/llvm/llvm-project/pull/164524