take endianness into account in arm64 fpsr xfer,
use VKI_LITTLE_ENDIAN to decide to reverse or not bytes in image function


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14223 a5019735-40e9-0310-863c-91ae7b9d1cf9
ensure the regcache is in sync with the fpsr part VEX represents
when fpsr is modified from gdb


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14225 a5019735-40e9-0310-863c-91ae7b9d1cf9