t9010 fails when no svn is available

Running test t9010 without svn currently errors out for no good reason.

The test uses "svnadmin" without checking if svn is available.  This was a
regression introduced by b0ad24b (t9010 (svn-fe): Eliminate dependency on
svn perl bindings, 2010-10-10) when it stopped including ./lib-git-svn.sh
that had the safety.

This should fix it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9010-svn-fe.sh

@@ -4,6 +4,12 @@ test_description='check svn dumpfile importer'
 
 . ./test-lib.sh
 
+if ! svnadmin -h >/dev/null 2>&1
+then
+	skip_all='skipping svn-fe tests, svn not available'
+	test_done
+fi
+
 svnconf=$PWD/svnconf
 export svnconf