[PATCH] MIPS support for --hash-style=gnu

[Koding]

Hi all,
	I am using this patch for a loongson 3A cpu。After some tests , I found that there was a mistake that cause many many alignment-faults in this patch.
	The patch added a Elf32_Word ngnusyms in the head of .gnu.xhash section, then "ElfW(Addr)  bitmask[maskwords]"  became unaligned(8-bytes).
	IMO, we should  change "Elf32_Word ngnusyms" to "Elf32_Xword ngnusyms" , or add 4-bytes pad after ngnusyms.