Fix some mishandling of the attr(gnu_inline) mode when used with
extern.  Previously we would warn about it and ignore the attribute.
This is incorrect, it should be handled as a c89 "extern inline" 
function.  Many thanks to Matthieu Castet for pointing this out and
beating me over the head until I got it.

PR3988: extern inline function are not externally visible




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69756 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed