hwf-x86: make stack unwinding work at i386 cpuid functions
* src/hwf-x86.c (FORCE_FUNC_FRAME_POINTER): New. [__i386__] (is_cpuid_available): Force use of stack frame pointer as inline assembly modifies stack register; Add 'memory' constraint for inline assembly. [__i386__] (get_cpuid): Avoid push/pop instruction when preserving %ebx register over cpuid.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>