Implemented parameter passing for function pointers

tests/programs/function-pointer.q

@@ -1,13 +1,12 @@
-import core
 import sys
 
 main() {
 	func := f
-	func()
+	func(0)
 	sys.exit(1)
 }
 
-f() {
-	exit := core.exit
-	exit()
+f(code int) {
+	exit := sys.exit
+	exit(code)
 }