Limits check in assembler seemed to break on 32 bit systems, fixed

Fix:
Replaced the integer literals with macros from the <climits.h>
library.

assembler/src/check.c

@@ -3,6 +3,7 @@
  *  - checking instruction parameters for their validity
  */
 #include <stdio.h>
+#include <limits.h>
 #include "../inc/msg.h"
 #include "../inc/global.h"
 
@@ -58,7 +59,7 @@ int unsigned4(int imm) {
  * imm: immediate to be checked
  */
 int word(int imm) {
-	if ((imm >= -2147483648) && (imm <= 2147483647)) {
+	if ((imm >= INT_MIN) && (imm <= INT_MAX)) {
 		// in valid range
 		return imm;
 	} else {