[gsound] build: Bump required gtk-doc version to 1.20

[Tristan Brindle <tbrindle src gnome org>]

commit 38f83652d85475d904de67274f98ea6ff2983b27
Author: Tristan Brindle <t c brindle gmail com>
Date:   Mon Dec 1 16:53:00 2014 +0800

    build: Bump required gtk-doc version to 1.20
    
    We're using Markdown doc comments which are only supported
    since gtk-doc 1.20, so bump the required version.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 8b2a1f1..8f015be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -37,7 +37,7 @@ PKG_CHECK_MODULES(GSOUND,
 AC_SUBST(GSOUND_CFLAGS)
 AC_SUBST(GSOUND_LIBS)
 
-GTK_DOC_CHECK(1.14, [--flavour no-tmpl])
+GTK_DOC_CHECK(1.20, [--flavour no-tmpl])
 
 GOBJECT_INTROSPECTION_CHECK([1.2.9])