add more extern C
    
    opcodes/ChangeLog:
    
    2016-06-01  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>
    
    	* nds32-asm.h: Add extern "C".
    	* sh-opc.h: Likewise.
    
    bfd/ChangeLog:
    
    2016-06-01  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>
    
    	* elf32-hppa.h: Add extern "C".
    	* elf32-nds32.h: Likewise.
    	* elf32-tic6x.h: Likewise.
    
    include/ChangeLog:
    
    2016-06-01  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>
    
    	* elf/mips.h: Likewise.
    	* elf/sh.h: Likewise.
    	* opcode/d10v.h: Likewise.
    	* opcode/d30v.h: Likewise.
    	* opcode/ia64.h: Likewise.
    	* opcode/mips.h: Likewise.
    	* opcode/ppc.h: Likewise.
    	* opcode/sparc.h: Likewise.
    	* opcode/tic6x.h: Likewise.
    	* opcode/v850.h: Likewise.