String buffer refactoring, part 4.

Add lua_State pointer to SBuf for buffer resizing.

src/lj_load.c

@@ -55,7 +55,7 @@ LUA_API int lua_loadx(lua_State *L, lua_Reader reader, void *data,
   ls.rdata = data;
   ls.chunkarg = chunkname ? chunkname : "?";
   ls.mode = mode;
-  lj_buf_init(&ls.sb);
+  lj_buf_init(L, &ls.sb);
   status = lj_vm_cpcall(L, NULL, &ls, cpparser);
   lj_lex_cleanup(L, &ls);
   lj_gc_check(L);