- fix mrbc_filename leak; cxt->filename would not be freed until the state is closed.

mrbgems/mruby-compiler/core/parse.y

@@ -5540,6 +5540,7 @@ mrbc_context_new(mrb_state *mrb)
 MRB_API void
 mrbc_context_free(mrb_state *mrb, mrbc_context *cxt)
 {
+  mrb_free(mrb, cxt->filename);
   mrb_free(mrb, cxt->syms);
   mrb_free(mrb, cxt);
 }
@@ -5549,9 +5550,12 @@ mrbc_filename(mrb_state *mrb, mrbc_context *c, const char *s)
 {
   if (s) {
     int len = strlen(s);
-    char *p = (char *)mrb_alloca(mrb, len + 1);
+    char *p = (char *)mrb_malloc(mrb, len + 1);
 
     memcpy(p, s, len + 1);
+    if (c->filename) {
+      mrb_free(mrb, c->filename);
+    }
     c->filename = p;
   }
   return c->filename;