[subset/cff1] Speed up plan_subset_charset

src/hb-subset-cff1.cc

@@ -556,7 +556,13 @@ struct cff1_subset_plan
       if (sid != last_sid + 1)
       {
 	code_pair_t pair { sid, glyph };
-	subset_charset_ranges.push (pair);
+	// This is stupid to do manually but it does show speedup.
+	// We should find up where the slowdown comes from in push()
+	// and fix it.
+	if ((int) subset_charset_ranges.length < subset_charset_ranges.allocated)
+	  subset_charset_ranges.arrayZ[subset_charset_ranges.length++] = pair;
+	else
+	  subset_charset_ranges.push (pair);
       }
       last_sid = sid;
     }