outobj: handle compilers without 64-bit switch() support

OpenWatcom, in particular, doesn't handle switch() statements with
64-bit expressions, sigh.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

output/outobj.c

@@ -43,6 +43,7 @@
 #include <string.h>
 #include <ctype.h>
 #include <inttypes.h>
+#include <limits.h>
 
 #include "nasm.h"
 #include "nasmlib.h"
@@ -1099,7 +1100,10 @@ static void obj_out(int32_t segto, const void *data,
 	    ldata -= size;
         }
 
-	switch (size) {
+	if (size > UINT_MAX)
+	    size = 0;
+
+	switch ((unsigned int)size) {
 	default:
 	    nasm_error(ERR_NONFATAL, "OBJ format can only handle 16- or "
 		       "32-byte relocations");