improve the diagnostic for uses of the GCC "global variable in a register" extension.
This implements rdar://6880449 - improve diagnostic for usage of "global register variable" GCC extension



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71599 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed