example: function calls can't happen on consts yet

- add suggestion to make it work as TODO

examples/hello.ry

@@ -4,8 +4,12 @@ fn f() i32 {
     return 2;
 }
 
+fn f2() i32 {
+    return f() + 2;
+}
+
 const (
-    piss = f() + 3
+    piss = 1 + 3
 )
 
 enum B {

src/codegen.zig

@@ -371,6 +371,9 @@ pub const Codegen = struct {
 
                     var global = llvm.LLVMAddGlobal(mod, const_llvm_type, const_name.ptr);
 
+                    // TODO maybe put builder at main function so we can still
+                    // call other functions inside consts?
+
                     var builder = llvm.LLVMCreateBuilder();
                     var expr_llvm_val = try self.emitExpr(builder, constdecl.expr);