jenkins: also test build in separate dir

To make sure that new patches don't break a build done in another dir than
srcdir, make jenkins verify that it still works.

Even though 'make distcheck' also tests a build from a separate dir, this does
not verify that BUILT_SOURCES are generated properly. If these already exist in
the source tree from a previous 'make' issued in the source tree, the
BUILT_SOURCES are not regenerated during 'make distcheck'. Hence a separate
test run is necessary to ensure stability of new patches.

Change-Id: I4b31538c155941fd241bcd33b0d39f2f8491ac1e
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index 656f02f..0c11682 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -10,3 +10,15 @@
   || cat-testlogs.sh
 $MAKE distcheck \
   || cat-testlogs.sh
+
+# verify build in dir other than source tree
+rm -rf *
+git checkout .
+autoreconf --install --force
+mkdir builddir
+cd builddir
+../configure --enable-static
+$MAKE $PARALLEL_MAKE check \
+  || cat-testlogs.sh
+$MAKE distcheck \
+  || cat-testlogs.sh