RuntimeDyldELF: don't create thunk if not needed
This patch doesn't create thunk for branch operation when following conditions are met:
- Architecture is AArch64
- Relocation target is in the same object file
- Relocation target is close enough to be encoded in immediate offset
In such case we branch directly to the target instead of branching to thunk
Differential revision: https://reviews.llvm.org/D28108
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291431 91177308-0d34-0410-b5e6-96231b3b80d8