[compiler-rt][test]Mark thinlto icp test as UNSUPPORTED on ppc. (#76008)

The test failure is about failed to build instrumented binary on ppc
(https://lab.llvm.org/buildbot/#/builders/18/builds/13228). Not sure how
to fix this for now. Mark the test unsupported on ppc.

```
RUN: at line 46: /home/buildbots/ppc64be-sanitizer/sanitizer-ppc64be/build/build_gcc/./bin/clang  --driver-mode=g++  -m64  -ldl  -fprofile-generate -fuse-ld=lld -O2 lib.cpp main.cpp -o main
+ /home/buildbots/ppc64be-sanitizer/sanitizer-ppc64be/build/build_gcc/./bin/clang --driver-mode=g++ -m64 -ldl -fprofile-generate -fuse-ld=lld -O2 lib.cpp main.cpp -o main
ld.lld: error: /lib/../lib64/Scrt1.o: ABI version 1 is not supported
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```