Fix "Since:" tags

Based on data from http://upstream-tracker.org/versions/harfbuzz.html
Resolves #103

src/hb-glib.cc

diff --git a/src/hb-glib.cc b/src/hb-glib.cc
index 61dff5e..7dbd83d 100644
--- a/src/hb-glib.cc
+++ b/src/hb-glib.cc
@@ -382,6 +382,9 @@
   return const_cast<hb_unicode_funcs_t *> (&_hb_glib_unicode_funcs);
 }
 
+/**
+ * Since: 0.9.38
+ **/
 hb_blob_t *
 hb_glib_blob_create (GBytes *gbytes)
 {