[Polly] Don't redundantly link libPolly into unittests.

With LLVM_LINK_LLVM_DYLIB and LLVM_POLLY_LINK_INTO_TOOLS, Polly is
already linked into libLLVM.so, linking libPolly.a as well into
unittests results in duplicate command line registration errors.

GitOrigin-RevId: cdbc86dd225063beb9fc8f6ba1f09afc18435331
1 file changed