configure: hardcode GRASS_VERSION_SVN=00000 for platforms without svnversion program available (needed for g.version)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@63880 15284696-431f-4ddb-bdfa-cd5b030d7da7

configure.in

@@ -126,12 +126,12 @@ changequote(,)
 LIB_VER=`echo ${GRASS_VERSION_NUMBER} | sed 's/^\([0-9.]*\).*$/\1/'`
 changequote([,])
 
-GRASS_VERSION_SVN=
+GRASS_VERSION_SVN=00000
 AC_PATH_PROG(SVN_VERSION, svnversion, no)
 if test "$SVN_VERSION" != "no" ; then
    GRASS_VERSION_SVN=`$SVN_VERSION -c | cut -f2 -d:`
    if test "$GRASS_VERSION_SVN" = "exported" -o "$GRASS_VERSION_SVN" = "Unversioned directory" ; then
-      GRASS_VERSION_SVN=
+      GRASS_VERSION_SVN=00000
    fi
 fi