[gxml] Set correct destiny dir for docs

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit c1a05621ae8fc2de300c4126675c948621458df0
Author: Antoine Jacoutot <ajacoutot gnome org>
Date:   Mon Apr 24 13:47:13 2017 -0500

    Set correct destiny dir for docs

 Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 35d404b..e640e7f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -17,7 +17,7 @@ DISTCHECK_CONFIGURE_FLAGS = \
 ### Specify files to include in dist
 
 # in share/doc/
-gxmldocdir = ${prefix}/doc/gxml
+gxmldocdir = ${datadir}/doc/gxml
 gxmldoc_DATA = \
        README \
        COPYING \