* elf32-mips.c (mips_elf_calculate_relocation): Fix overflow handling

	* elf32-mips.c (mips_elf_calculate_relocation): Fix overflow handling
	of R_MIPS_PC16.

	* config/tc-mips.c (append_insn): Handle BFD_RELOC_16_PCREL.
	(macro_build): Use BFD_RELOC_16_PCREL_S2 only for embedded
	PIC, BFD_RELOC_16_PCREL for the rest.
	(mips_ip): Likewise.
        (md_pcrel_from): return the right offset for the differently shifted
        pcrel relocs.
	(md_apply_fix): Handle BFD_RELOC_16_PCREL.

	* gas/mips/beq.d: Check branches to external labels.
	* gas/mips/beq.s: Likewise.
	* gas/mips/bge.d: Likewise.
	* gas/mips/bge.s: Likewise.
	* gas/mips/bgeu.d: Likewise.
	* gas/mips/bgeu.s: Likewise.
	* gas/mips/blt.d: Likewise.
	* gas/mips/blt.s: Likewise.
	* gas/mips/bltu.d: Likewise.
	* gas/mips/bltu.s: Likewise.
	* gas/mips/elempic.d: Switch from R_MIPS_GNU_REL16_S2 to R_MIPS_PC16.
	* gas/mips/empic.d: Likewise.
	* gas/mips/empic.s: Likewise.
	* gas/mips/telempic.d: Likewise.
	* gas/mips/tempic.d: Likewise.