PPC64, Valgrind with GDB does not display 64-bit and 128-bit registers

PPC64, Valgrind with GDB does not display 64-bit and 128-bit registers
correctly

1)  Fix Endianess issue that was missed in the BE to LE port.  GDB was
    not displaying the contents of the 64-bit and 128-bit registers
    correctly due to an Endianess issue.

2)  Fix displaying the shadow registers for the 64-bit and 128-bit
    registers.

Bugzilla 360008 was opened for this issue.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15864