Clang 13 has a -fsanitize-coverage -fno-semantic-interposition bug (D117190)
which may lead to
relocation R_X86_64_PC32 cannot be used against symbol linker error
in -DLLVM_USE_SANITIZE_COVERAGE=ON build when a shared object is built (e.g.
For simplicity, just disallow Clang 13 entirely.
Note: GCC -fPIC performance benefits from -fno-semantic-interposition
dramatically. Clang benefits little. Using this option is more for a dogfood
purpose to test correctness of this option, because in the wild some important
packages like CPython uses this option.