dsp/cpu: NaCl has no support for xgetbv

or the raw opcode; fixes:
  934ed4: unrecognized instruction

Change-Id: I981870baf0e8b03bf40144ea8ec25eff140d5bc3
fix for gcc-4.9 warnings about longjmp + local variables

Needed to add 'volatile' and some casts.
Relevant excerpt from the 'man longjmp':

===============
The values of automatic variables are unspecified after a call to longjmp() if they meet all the following criteria:
  ·  they are local to the function that made the corresponding setjmp(3) call;
  ·  their values are changed between the calls to setjmp(3) and longjmp(); and
  ·  they are not declared as volatile.
===============

Change-Id: Ic72dc92669513a820369ca52a038afa9ec88091f