bfd * elfnn-aarch64.c (elfNN_aarch64_relocate_section): Add a more
helpful warning message to explain why certain AArch64 relocs
might overflow.
ld * testsuite/ld-aarch64/reloc-overflow-bad.d: New test.
* testsuite/ld-aarch64/reloc-overflow-1.s: New source file.
* testsuite/ld-aarch64/reloc-overflow-2.s: New source file.
* testsuite/ld-aarch64/aarch64-elf.exp: Run the new test.