Make initial shape hash table bigger (#1120)

Even an empty script requires more than 16 entries in the hash table.

Before this commit, executing an empty script caused the hash table
to resize two times. Now, it's the proper size from the start and
not resized at all.

Author: bnoordhuis

quickjs.c

@@ -4429,7 +4429,7 @@ static inline JSShapeProperty *get_shape_prop(JSShape *sh)
 
 static int init_shape_hash(JSRuntime *rt)
 {
-    rt->shape_hash_bits = 4;   /* 16 shapes */
+    rt->shape_hash_bits = 6;   /* 64 shapes */
     rt->shape_hash_size = 1 << rt->shape_hash_bits;
     rt->shape_hash_count = 0;
     rt->shape_hash = js_mallocz_rt(rt, sizeof(rt->shape_hash[0]) *