libtheora: fixed to not build documentation for the format specifications if ghostscript is not available

multimedia/libtheora/libtheora.conf

@@ -0,0 +1,19 @@
+# --- SDE-COPYRIGHT-NOTE-BEGIN ---
+# This copyright note is auto-generated by ./scripts/Create-CopyPatch.
+#
+# Filename: package/.../libtheora/libtheora.conf
+# Copyright (C) 2010 The OpenSDE Project
+#
+# More information can be found in the files COPYING and README.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License. A copy of the
+# GNU General Public License can be found in the file COPYING.
+# --- SDE-COPYRIGHT-NOTE-END ---
+
+# Do not try to build documentation for the format specification
+# if ghostscript is not installed
+if ! pkginstalled -f ghostscript; then
+	var_append extraconfopt ' ' "--disable-spec"
+fi