build: Fixes for make check.

* build-aux/config.sh (srcdir): Initialize if unset.
* build-aux/test.sh (DIFF): Do not fail if unset.

build-aux/config.sh

@@ -16,6 +16,7 @@
 # You should have received a copy of the GNU General Public License
 # along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
 
+srcdir=${srcdir-.}
 if [ "$V" = 2 ]; then
     echo $0
     echo srcdest=${srcdest}

build-aux/test.sh

@@ -25,15 +25,12 @@ set -e
 MES_ARENA=100000000
 
 GUILE=${GUILE-$MES}
-DIFF=${DIFF-$(command -v diff)}
+DIFF=${DIFF-$(command -v diff)} || true
 [ -z "$DIFF" ] && DIFF="sh scripts/diff.scm"
 
 t=${1-scaffold/tests/t}
 o="$t"
 rm -f "$o".mes-out
-shift
-
-set -e
 
 rm -f "$o".gcc-out
 if [ -n "$CC" ]; then