Fix build on gcc 4.8

Commit def5fbbb6ff9fd077ee5683c34bfd549fc745413 added
no_instrument_functions to a bunch of "extern inline" functions which
cannot be instrumented because they are only inlined. Unfortunately,
this doesn't work in gcc 4.8 because of a gcc bug only fixed in 4.9:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49718

So this patch undoes the fix of that patch, and insteads
tells the compiler, via a command line option, not to instrument anything
in those *mmintrin.h header. This also solves the original problem, and
works on gcc 4.8 as well.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>