PowerPC64 little-endian fixes: structure passing

PowerPC64 little-endian fixes: structure passing

When passing a small structure in a GPR, the ABI specifies that it
should be passed in the least-significant bytes of the register
(or stack slot).  On big-endian systems, this means the value
needs to be stored at an offset, which is what current code does.

However, on little-endian systems, the least-significant bytes are
addresses with offset 0.  This patch fixes that.

gdb/ChangeLog:

	* ppc-sysv-tdep.c (ppc64_sysv_abi_push_val): Use correct
	offset on little-endian when passing small structures.