[llvm] [compiler-rt] follow-up to 166837, rename COMPILER_RT_FORCE_TEST_BUILTINS_DIR to COMPILER_RT_TEST_BUILTINS_DIR (PR #171741)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64-aix` running on `aix-ppc64` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/64/builds/6777

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Builtins-powerpc-aix :: ashrdi3_test.c' FAILED ********************
Exit Code: 8

Command Output (stdout):
--
# RUN: at line 1
/home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/./bin/clang   -gline-tables-only  -m32  -fno-builtin -I /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/compiler-rt/lib/builtins -nodefaultlibs /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/compiler-rt/test/builtins/Unit/ashrdi3_test.c /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/./lib/../lib/clang/22/lib/powerpc64-ibm-aix/libclang_rt.builtins.a -lc -lm -o /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/runtimes/runtimes-bins/compiler-rt/test/builtins/Unit/POWERPCAIXConfig/Output/ashrdi3_test.c.tmp &&  /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/runtimes/runtimes-bins/compiler-rt/test/builtins/Unit/POWERPCAIXConfig/Output/ashrdi3_test.c.tmp
# executed command: /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/./bin/clang -gline-tables-only -m32 -fno-builtin -I /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/compiler-rt/lib/builtins -nodefaultlibs /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/llvm-project/compiler-rt/test/builtins/Unit/ashrdi3_test.c /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/./lib/../lib/clang/22/lib/powerpc64-ibm-aix/libclang_rt.builtins.a -lc -lm -o /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/runtimes/runtimes-bins/compiler-rt/test/builtins/Unit/POWERPCAIXConfig/Output/ashrdi3_test.c.tmp
# .---command stderr------------
# | ld: 0711-317 ERROR: Undefined symbol: .__ashrdi3
# | ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
# | clang: error: linker command failed with exit code 8 (use -v to see invocation)
# `-----------------------------
# error: command failed with exit status: 8

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/171741