Make LLVM_PRETTY_FUNCTION support __func__.

In case there are compilers that support neither __FUNCSIG__ or
__PRETTY_FUNCTION__, we fall back to __func__ as a last resort,
which should be guaranteed by C++11 and C99.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278176 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed