x86: Reinstate hand-written unwind info for sysv.S
x86: Reinstate hand-written unwind info for sysv.S

bgarrels/libffi,Pan7/libffi,biosbits/libffi,rth7680/libffi,bgarrels/libffi,biosbits/libffi,Distrotech/libffi,biosbits/libffi,nmav/libffi,plicease/libffi,nmav/libffi,plicease/libffi,Pan7/libffi,nmav/libffi,joshtriplett/libffi,rth7680/libffi,s1341/libffi,rth7680/libffi,nmav/libffi,joshtriplett/libffi,Distrotech/libffi,plicease/libffi,Distrotech/libffi,bgarrels/libffi,Distrotech/libffi,bgarrels/libffi,s1341/libffi,s1341/libffi,joshtriplett/libffi,rth7680/libffi,biosbits/libffi,Pan7/libffi,s1341/libffi,plicease/libffi,Pan7/libffi,joshtriplett/libffi