[AArch 64] Use a constant pool load for weak symbol references when
using static relocation model and small code model.
Summary: currently we generate GOT based relocations for weak symbol
references regardless of the underlying relocation model. This should
be change so that in static relocation model we use a constant pool
load instead.
Patch from: Keith Walker
Reviewers: Renato Golin, Tim Northover
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217503
91177308-0d34-0410-b5e6-
96231b3b80d8