Suppress the c++11 -Wdeprecated warning for 'register' if it is expanded from a
macro defined in a system header. glibc uses it in macros, apparently.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184005 91177308-0d34-0410-b5e6-96231b3b80d8