Before this change, func Hello() of mypkg package generated a function
GoMypkg_Hello to distinguish the prefix from the function name.
It seems the use of '_' is very rare in Objective-C though.
After this change, it generates GoMypkgHello.
Change-Id: Ic7aa2b667363a447a5ff3500262502d3137d6853
Reviewed-on: https://go-review.googlesource.com/11893
Reviewed-by: Damien Neil <dneil@google.com>