Fix GNU ObjC ABI for a message returning a struct.

This allows the ObjFW runtime to correctly implement message forwarding
for messages which return a struct.

Patch by Jonathan Schleifer.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187174 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed