Make sure system "..." returns successfully

We didn't check the return status of system, making failures in a00009
go unnoticed.  Fix this and fix a00009 to not fail when run
uninstalled.


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3826 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishtest/tests/a00009.vtc

@@ -2,4 +2,4 @@
 
 test "See that the VCL compiler works"
 
-shell "cd ../varnishd && ./varnishd -b 127.0.0.1:80 -C"
+shell "cd ../varnishd && ./varnishd -b 127.0.0.1:80 -C -n /tmp/__v1"

bin/varnishtest/vtc.c

@@ -246,7 +246,7 @@ cmd_shell(CMD_ARGS)
 	AN(av[1]);
 	AZ(av[2]);
 	vtc_dump(vl, 4, "shell", av[1]);
-	(void)system(av[1]);	/* XXX: assert ? */
+	assert(WEXITSTATUS(system(av[1])) == 0);
 }
 
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