autotools: fix doc install on old systems.

diff --git a/doc/Makefile.am b/doc/Makefile.am
index 0cf65729652acf998bd93ef9ef6e23ca78f47c87..e507b07b0e25d7f2a76caf8800a7beefcf1d518b 100644 (file)
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -30,4 +30,5 @@ Ubuntu_Installation.txt \
 Ubuntu_Installation_from_GIT.txt \
 Windows.txt
 
+docdir = ${datarootdir}/doc/${PACKAGE}
 dist_doc_DATA = ${EXTRA_DIST}