BUG/MINOR: init: -x can have a parameter starting with a dash

There is no reason the -x option can't take an argument which starts with
a -. This limitation must only be used for options that take a
non-finite list of parameters (-sf/-st)

This can be backported only if the previous patch which fixes
copy_argv() is backported too.

Could be backported as far as 1.8.
diff --git a/src/haproxy.c b/src/haproxy.c
index 3727486..ed971a4 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1868,7 +1868,7 @@
 			else if (*flag == 'q')
 				arg_mode |= MODE_QUIET;
 			else if (*flag == 'x') {
-				if (argc <= 1 || argv[1][0] == '-') {
+				if (argc <= 1) {
 					ha_alert("Unix socket path expected with the -x flag\n\n");
 					usage(progname);
 				}