set name to each library

src/gc.c

@@ -399,6 +399,7 @@ gc_mark_object(pic_state *pic, struct pic_object *obj)
   }
   case PIC_TT_LIB: {
     struct pic_lib *lib = (struct pic_lib *)obj;
+    gc_mark(pic, lib->name);
     gc_mark_object(pic, (struct pic_object *)lib->senv);
     break;
   }

src/lib.c

@@ -12,6 +12,7 @@ pic_make_library(pic_state *pic, pic_value name)
   lib = (struct pic_lib *)pic_obj_alloc(pic, sizeof(struct pic_lib), PIC_TT_LIB);
   lib->senv = pic_core_syntactic_env(pic);
   lib->exports = xh_new();
+  lib->name = name;
 
   /* register! */
   pic->lib_tbl = pic_acons(pic, name, pic_obj_value(lib), pic->lib_tbl);