[llgo] Remove support for LLVM attributes

llgo supports the application of LLVM attributes to global objects
and functions.  This "feature" is undocumented and untested.  As
discusses in D27442, it should be removed.

Differential Revision: https://reviews.llvm.org/D27474

llvm-svn: 288843
GitOrigin-RevId: e6c29d6d854cbbafc108cf32f9676157464f39fc
1 file changed