suppress sh assembler rejection of instructions based on isa level

we need access to all instructions in order for runtime selection of
atomic model to work correctly. without this patch, some versions of
gcc instruct gas to reject instructions outside the target isa level.

configure

@@ -556,6 +556,7 @@ test "$ARCH" = "microblaze" && trycppif __MICROBLAZEEL__ "$t" \
 && SUBARCH=${SUBARCH}el
 
 if test "$ARCH" = "sh" ; then
+tryflag CFLAGS_AUTO -Wa,--isa=any
 trycppif __BIG_ENDIAN__ "$t" && SUBARCH=${SUBARCH}eb
 if trycppif "__SH_FPU_ANY__ || __SH4__" "$t" ; then
 # Some sh configurations are broken and replace double with float