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.

binutils/testsuite/binutils-all/mips/mips-reginfo-n32.d

@@ -0,0 +1,7 @@
+#PROG: objcopy
+#name: MIPS objcopy .reginfo section size (n32)
+#as: -n32 -mips3
+#objcopy: --rename-section .foo=.reginfo
+#source: mips-reginfo.s
+#error: \A[^\n]*: Incorrect `\.reginfo' section size; expected 24, got 4\n
+#error:   [^\n]*: Bad value\Z

binutils/testsuite/binutils-all/mips/mips-reginfo.d

@@ -0,0 +1,6 @@
+#PROG: objcopy
+#name: MIPS objcopy .reginfo section size
+#as: -32
+#objcopy: --rename-section .foo=.reginfo
+#error: \A[^\n]*: Incorrect `\.reginfo' section size; expected 24, got 4\n
+#error:   [^\n]*: Bad value\Z

binutils/testsuite/binutils-all/mips/mips-reginfo.s

@@ -0,0 +1,2 @@
+	.section .foo, "a"
+	.word	0xdeadbeef

binutils/testsuite/binutils-all/mips/mips.exp

@@ -60,3 +60,8 @@ if $has_newabi {
     run_dump_test "mips-note-2r-n32"
     run_dump_test "mips-note-2r-n64"
 }
+
+run_dump_test "mips-reginfo"
+if $has_newabi {
+    run_dump_test "mips-reginfo-n32"
+}