Add a proptest for the JIT backend.

runtime/rts.c

@@ -1,12 +1,12 @@
 #include <stdint.h>
 #include <stdio.h>
 
-void print(char *variable_name, uint64_t value) {
+void print(char *_ignore, char *variable_name, uint64_t value) {
     printf("%s = %llii64\n", variable_name, value);
 }
 
 void caller() {
-    print("x", 4);
+    print(NULL, "x", 4);
 }
 
 extern void gogogo();