Disable gtk-doc macro

We don't have any docs yet.
diff --git a/configure.ac b/configure.ac
index 856fb98..32148ea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -49,7 +49,7 @@
 HB_LIBTOOL_VERSION_INFO=hb_libtool_current:hb_libtool_revision:hb_libtool_age
 AC_SUBST(HB_LIBTOOL_VERSION_INFO)
 
-GTK_DOC_CHECK([1.15],[--flavour no-tmpl])
+dnl GTK_DOC_CHECK([1.15],[--flavour no-tmpl])
 
 # Functions and headers
 AC_CHECK_FUNCS(mprotect sysconf getpagesize mmap _setmode)