[Fuzzer] Avoid C++ compiler checks for fuzzer C++ library
[Fuzzer] Avoid C++ compiler checks for fuzzer C++ library

When bulding libFuzzer as part of the toolchain, C++ library may not
have been fully built yet so the C++ compiler checks will fail, but we
don't care since we don't need C++ library anyway as we're building
our own.

Differential Revision: https://reviews.llvm.org/D45638

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@330075 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt