fix"string compare works differently in simulator/on target"

libs/core/core.cpp

@@ -21,7 +21,12 @@ namespace String_ {
 
     //%
     int compare(StringData *s, StringData *that) {
-        return strcmp(s->data, that->data);
+        int compareResult = strcmp(s->data, that->data);
+        if (compareResult < 0)
+          return -1;
+        else if (compareResult > 0)
+          return 1;
+        return 0;
     }
 
     //%