[repacker] Use hb_pair_t constructor instead of hb_pair ().

hb_pair was causing corrupted gid values.

src/graph/pairpos-graph.hh

@@ -351,19 +351,19 @@ struct PairPosFormat2 : public OT::Layout::GPOS_impl::PairPosFormat2_4<SmallType
     ClassDef* class_def_1_table = (ClassDef*) class_def_1_v.obj.head;
     if (!coverage_table->sanitize (coverage_v)
         || !class_def_1_table->sanitize (class_def_1_v))
-      return false;
+      return -1;
 
     auto klass_map =
     + coverage_table->iter ()
     | hb_map_retains_sorting ([&] (hb_codepoint_t gid) {
-      return hb_pair (gid, class_def_1_table->get_class (gid));
+      return hb_pair_t<hb_codepoint_t, hb_codepoint_t> (gid, class_def_1_table->get_class (gid));
     })
     | hb_filter ([&] (hb_codepoint_t klass) {
       return klass >= start && klass < end;
     }, hb_second)
     | hb_map_retains_sorting ([&] (hb_pair_t<hb_codepoint_t, hb_codepoint_t> gid_and_class) {
       // Classes must be from 0...N so subtract start
-      return hb_pair (gid_and_class.first, gid_and_class.second - start);
+      return hb_pair_t<hb_codepoint_t, hb_codepoint_t> (gid_and_class.first, gid_and_class.second - start);
     })
     ;
 
@@ -492,7 +492,7 @@ struct PairPosFormat2 : public OT::Layout::GPOS_impl::PairPosFormat2_4<SmallType
     auto klass_map =
     + coverage_table->iter ()
     | hb_map_retains_sorting ([&] (hb_codepoint_t gid) {
-      return hb_pair (gid, class_def_1_table->get_class (gid));
+      return hb_pair_t<hb_codepoint_t, hb_codepoint_t> (gid, class_def_1_table->get_class (gid));
     })
     | hb_filter ([&] (hb_codepoint_t klass) {
       return klass < count;