MIPS/BFD: Correctly report unsupported `.reginfo' section size

MIPS/BFD: Correctly report unsupported `.reginfo' section size

Report an error when an unsupported `.reginfo' section size is found in
`_bfd_mips_elf_section_processing', removing an assertion that triggers
at elfxx-mips.c:7105 in GAS when assembling input like:

	.section	.reginfo
	.word		0xdeadbeef

and in `objcopy --rename-section' when renaming an incorrectly sized
section to `.reginfo'.

	bfd/
	* elfxx-mips.c (_bfd_mips_elf_section_processing): For
	SHT_MIPS_REGINFO sections don't assert the correct size and
	report an error instead.

	binutils/
	* testsuite/binutils-all/mips/mips-reginfo.d: New test.
	* testsuite/binutils-all/mips/mips-reginfo-n32.d: New test.
	* testsuite/binutils-all/mips/mips-reginfo.s: New test source.
	* testsuite/binutils-all/mips/mips.exp: Run the new tests.

	gas/
	* testsuite/gas/mips/reginfo-2.d: New test.
	* testsuite/gas/mips/reginfo-2-n32.d: New test.
	* testsuite/gas/mips/reginfo-2.l: New test stderr output.
	* testsuite/gas/mips/reginfo-2.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.