Refine fenv.h handling: check if the desired macros exist, before using
it. NetBSD/ARM and TILE-Gx are examples for platforms that have an
unusable fenv.h and this avoids the need for a blacklist.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177865 91177308-0d34-0410-b5e6-96231b3b80d8
Don't use add_llvm_definitions for adding warning flags.  It makes it too hard
to have them appear in the right order.  Instead append all warnings explicitly
to the language flags.  This was already the case for many warnings.  Fixes the
issue of -Wno-maybe-uninitialized not being effective because -Wall was being
placed after it rather than before.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177866 91177308-0d34-0410-b5e6-96231b3b80d8
Add a GC plugin for Erlang

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177867 91177308-0d34-0410-b5e6-96231b3b80d8