Internally use hb_malloc/.../hb_free instead of malloc/.../free

Redefining those stock names as macros was conflicting with gcc 10
headers.

Fixes https://github.com/harfbuzz/harfbuzz/issues/3044
diff --git a/src/hb-ot-shape-complex-indic.cc b/src/hb-ot-shape-complex-indic.cc
index 0594f31..aff615f 100644
--- a/src/hb-ot-shape-complex-indic.cc
+++ b/src/hb-ot-shape-complex-indic.cc
@@ -257,7 +257,7 @@
 static void *
 data_create_indic (const hb_ot_shape_plan_t *plan)
 {
-  indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
+  indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) hb_calloc (1, sizeof (indic_shape_plan_t));
   if (unlikely (!indic_plan))
     return nullptr;
 
@@ -300,7 +300,7 @@
 static void
 data_destroy_indic (void *data)
 {
-  free (data);
+  hb_free (data);
 }
 
 static indic_position_t