Sink the _GNU_SOURCE definition down into the target configuration,
and only define it where we know we need it---Linux and Cygwin. Thanks
to Chris for the prodding.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101989 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed