added functions to stop COUNT

cMIPS/include/cMIPS.h

@@ -46,6 +46,7 @@ extern void disableInterr(void);
 
 // internal counter, CP0 register COUNT
 extern int startCount(void);
+extern int stopCount(void);
 extern int readCount(void);
 
 extern char *memcpy(char*, const char*, int);