[libFuzzer] Check for target(popcnt) capability before usage

Older compilers (e.g. LLVM 3.4) do not support the attribute target("popcnt").
In order to support those, this diff check the attribute support using the preprocessor.

Patch by George Karpenkov.

Differential Revision: https://reviews.llvm.org/D32311



git-svn-id: svn://svn.chromium.org/llvm-project/llvm/trunk/lib/Fuzzer@300999 0b72dbe1-c17f-4bc7-b9db-2b4152be0356
1 file changed