[compiler-rt] [compiler-rt] [Fuzzer] Fix ARMv7 test link failure by linking unwinder (PR #144495)

[Leandro Lupori via llvm-commits]

luporl wrote:

It seems FUZZER_UNWINDER_LIBS should have been passed to LINK_LIBS.
Instead it was added to LIBFUZZER_UNITTEST_LINK_FLAGS, that is later passed to LINK_FLAGS.

https://github.com/llvm/llvm-project/pull/144495