Add mips*-img-elf* target triple.

Add mips*-img-elf* target triple.

/
	* configure.ac: Add mips*-img-elf* target triple.
	* configure: Regenerate.

bfd/
	* config.bfd: Add mips*-img-elf* target triple.

gas/
	* configure.tgt: Add mips*-img-elf* target triple.

gas/testsuite/
	* gas/mips/mips.exp: Add mips*-img-elf* target triple.

binutils/testsuite/
	* binutils-all/objcopy.exp: Add mips*-img-elf* target triple.
	* binutils-all/readelf.exp: Likewise.

ld/
	* configure.tgt: Add mips*-img-elf* target triple.

ld/testsuite/
	* ld-mips-elf/mips-elf.exp: Add support for mips*-img-elf* target
	triple.