bump product version to 7.1.8.0.0+

Change-Id: I3ba1585241bd069a582a311c8c1e5c142c937a7b
diff --git a/configure.ac b/configure.ac
index 83b67fd..a9c4b15 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,7 @@ dnl in order to create a configure script.
# several non-alphanumeric characters, those are split off and used only for the
# ABOUTBOXPRODUCTVERSIONSUFFIX in openoffice.lst. Why that is necessary, no idea.

AC_INIT([LibreOffice],[7.1.7.0.0+],[],[],[http://documentfoundation.org/])
AC_INIT([LibreOffice],[7.1.8.0.0+],[],[],[http://documentfoundation.org/])

dnl libnumbertext needs autoconf 2.68, but that can pick up autoconf268 just fine if it is installed
dnl whereas aclocal (as run by autogen.sh) insists on using autoconf and fails hard