Add new relocations to GAS

Add new relocations to GAS

Also add the ability to disassemble these relocations correctly.

Include checking that many different sizes work with different
instructions, include error checking that the `size` relocation is not
allowed in a64 mode.  Ensure that the size relocation is not allowed on
instructions other than mov[kz].

See the arm ABI aaelf64-morello document for the definition of these
new relocations.

Regenerate bfd/bfd-in2.h and bfd/libbfd.h from bfd/reloc.c.