Add -mno-movbe to disable "movbe" instruction from code-gen

Add -mno-movbe to disable "movbe" instruction from code-gen

Intruction "movbe" (move data after swapping bytes) is only available in
Intel atom.  Disable it for more general x86 devices and x86 hosts which
run emulator-x86.  Although emulator-x86 can support "movbe", most of
the time we want to run emulator-x86 with VT support for speed (with KVM
in Linux, or HAXM in Windows/MacOSX).  The presence of "movbe" can crash
emulator-x86 in VT because non-atom host doesn't have it natively.

Change-Id: I86e037900ddcb8d544f92b8d8464c8627347e560