Replace REPLACEME's left out of 2.4.0

https://github.com/harfbuzz/harfbuzz/issues/1641

src/hb-common.h

diff --git a/src/hb-common.h b/src/hb-common.h
index fbabd71..371b2bf 100644
--- a/src/hb-common.h
+++ b/src/hb-common.h
@@ -358,7 +358,7 @@
   /*11.0*/HB_SCRIPT_SOGDIAN			= HB_TAG ('S','o','g','d'),
 
   /*
-   * Since REPLACEME
+   * Since 2.4.0
    */
   /*12.0*/HB_SCRIPT_ELYMAIC			= HB_TAG ('E','l','y','m'),
   /*12.0*/HB_SCRIPT_NANDINAGARI			= HB_TAG ('N','a','n','d'),

src/hb-directwrite.cc

diff --git a/src/hb-directwrite.cc b/src/hb-directwrite.cc
index 137cd56..cbf04a8 100644
--- a/src/hb-directwrite.cc
+++ b/src/hb-directwrite.cc
@@ -918,7 +918,7 @@
 /**
  * hb_directwrite_face_create:
  * @font_face:
- * Since: REPLACEME
+ * Since: 2.4.0
  **/
 hb_face_t *
 hb_directwrite_face_create (IDWriteFontFace *font_face)

src/hb-subset-input.cc

diff --git a/src/hb-subset-input.cc b/src/hb-subset-input.cc
index 693c9c2..4d203b5 100644
--- a/src/hb-subset-input.cc
+++ b/src/hb-subset-input.cc
@@ -152,7 +152,7 @@
  * hb_subset_input_set_retain_gids:
  * @subset_input: a subset_input.
  * @retain_gids: If true the subsetter will not renumber glyph ids.
- * Since: REPLACEME
+ * Since: 2.4.0
  **/
 HB_EXTERN void
 hb_subset_input_set_retain_gids (hb_subset_input_t *subset_input,
@@ -164,7 +164,7 @@
 /**
  * hb_subset_input_get_retain_gids:
  * Returns: value of retain_gids.
- * Since: REPLACEME
+ * Since: 2.4.0
  **/
 HB_EXTERN hb_bool_t
 hb_subset_input_get_retain_gids (hb_subset_input_t *subset_input)