only emit global section when not empty

random.cwa

@@ -1,19 +1,6 @@
 import "env.memory" memory(4);
-
-global mut randomState: i32 = 37;
-
-fn random() -> i32 {
-    let state: i32;
-    randomState = (state := (
-                          state := randomState ^ (randomState << 13)
-                      ) ^ (state >> 17)
-                  ) ^ (state << 5);
-    randomState * 625341585
-}
-
-fn seed(s: i32) {
-    randomState = (((s + !(s >> 31)) as i64 * 8445297036689579347i64) >> 31i64) as i32;
-}
+import "env.random" fn random() -> i32;
+import "env.randomSeed" fn seed(i32);
 
 export fn tic(time: i32) {
     let i: i32;

src/emit.rs

@@ -112,7 +112,9 @@ pub fn emit(script: &ast::Script) -> Vec<u8> {
         }
 
         module.section(&functions);
+        if !script.global_vars.is_empty() {
             module.section(&global_section);
+        }
         module.section(&exports);
         module.section(&code);
     }