Fix struct function ordering in c files

programs/base_test.kl

@@ -3,7 +3,7 @@
 main :: (argc: int, argv: **char): int
   arena: Arena
   arena_init(&arena)
-  data: *S64 = allocate((&arena)->*Allocator, size_of(S64))
+  data: *S64 = arena_push_size(&arena, size_of(S64))
   *data = 10
 
   arena_release(&arena)