[JITLink][MachO][arm64] Build GOT entries for defined symbols too.

During the generic x86-64 support refactor in ecf6466f the implementation
of MachO_arm64_GOTAndStubsBuilder::isGOTEdgeToFix was altered to only return
true for external symbols. This behavior is incorrect: GOT entries may be
required for defined symbols (e.g. in the large code model).

This patch fixes the bug and adds a test case for it (renaming an old test
case to avoid any ambiguity).