Dynamic asan tests don't find libclang_rt.asan.so

[rorth]

The 32-bit dynamic asan unit tests FAIL to find libclang_rt.asan.so at runtime on Solaris/amd64:

  AddressSanitizer-Unit :: ./Asan-i386-calls-Dynamic-Test/failed_to_discover_tests_from_gtest
  AddressSanitizer-Unit :: ./Asan-i386-inline-Dynamic-Test/failed_to_discover_tests_from_gtest

The problem is that either or both of LD_LIBRARY_PATH* and the RUNPATH aren't set correctly for various reasons detailed in PR #100083.

I'd like the patch to go into the 19.x release once approved/committed to main.

[rorth]

/cherry-pick c34d673

[llvmbot]

/pull-request #100322