mark all vfp registers as used when done.

To avoid assigning registers the would fit, once arguments have been on
the stack, we mark all registers as used once we do not find a free
register for the first time.

src/arm/ffi.c

@@ -897,6 +897,9 @@ static void place_vfp_arg (ffi_cif *cif, ffi_type *t)
       return;
     next_reg: ;
     }
+	// done mark all regs as used
+	cif->vfp_reg_free = 16;
+	cif->vfp_used = 0xFFFF;
 }
 
 static void layout_vfp_args (ffi_cif *cif)