Import 0.15.1 vendor code.
Merge branch 'vendor' to get 0.15.1 code.

Conflicts:
	Makefile.objs
	cpu-exec.c
	fpu/softfloat-native.h
	fpu/softfloat.h
Only include syscall.h when needed.

This makes the build not fail for platforms where it isn't available
and therefore disabled by configure.
Add libbsd on Haiku for the daemon() function.
Only use SIGIO if it is defined at all.