bash: fix lp #496114, fetch patches in XBPS_SRCDISTDIR.

--HG--
extra : convert_revision : 0305e5fb2a0ec9c2545af0d6c938d0769fa0ba96

srcpkgs/bash/template

@@ -44,6 +44,7 @@ pre_configure()
 	local url="http://ftp.gnu.org/gnu/bash/bash-4.0-patches"
 
 	if [ "${bash_patchlevel}" -gt 000 ]; then
+		cd ${XBPS_SRCDISTDIR} || return 1
 		for p in $(seq -w 001 ${bash_patchlevel}); do
 			[ -f ${XBPS_SRCDISTDIR}/bash40-${p} ] && continue
 			$XBPS_FETCH_CMD ${url}/bash40-$p