Avoid permissions issues with the UDS in permutations*.vtc.

We've had reports of these tests failing on some platforms (e.g.
FreeBSD 13), with FetchError reporting EPERM for the backend that
accesses the UDS.

Since it's not a pesi issue, and not related to the properties under
test, we might as well allow fully open access to the UDS.

src/tests/permutations-error.vtc

@@ -37,7 +37,7 @@ server s2 -repeat 2 -keepalive {
 	chunkedlen 0
 } -start
 
-varnish v1 -arg "-a 127.0.0.1:0 -a self=${tmpdir}/v1.sock" \
+varnish v1 -arg "-a 127.0.0.1:0 -a self=${tmpdir}/v1.sock,mode=777" \
 	-arg "-p first_byte_timeout=5" \
 	-arg "-p between_bytes_timeout=5" \
 	-arg "-p backend_idle_timeout=1" \

src/tests/permutations.vtc

@@ -37,7 +37,7 @@ server s2 -repeat 2 -keepalive {
 	chunkedlen 0
 } -start
 
-varnish v1 -arg "-a 127.0.0.1:0 -a self=${tmpdir}/v1.sock" \
+varnish v1 -arg "-a 127.0.0.1:0 -a self=${tmpdir}/v1.sock,mode=777" \
 	-arg "-p first_byte_timeout=5" \
 	-arg "-p between_bytes_timeout=5" \
 	-arg "-p backend_idle_timeout=1" \