don't try the normal GetOrCreateLLVM. The latter could drop the weak
atrtibute on the second reference, if there is no explicit declaration
of the aliasee.
llvm-svn: 166032
Clang's support for weakref is now better than llvm-gcc's :-)
We don't introduce a new symbol and we correctly mark undefined references weak only if there is no
definition or regular undefined references in the same file.
llvm-svn: 97733
Stephen Lin