MEDIUM: init: support a list of files on the command line

HAProxy could already support being passed a file list on the command
line, by passing multiple times "-f" followed by a file name. People
have been complaining that it made it hard to pass file lists from init
scripts.

This patch introduces an end of arguments using the common "--" tag,
after which only file names may appear. These files are then added to
the existing list of other files specified using -f and are loaded in
their declaration order. Thus it becomes possible to do something like
this :

    haproxy -sf $(pidof haproxy) -- /etc/haproxy/global.cfg /etc/haproxy/customers/*.cfg
diff --git a/src/haproxy.c b/src/haproxy.c
index 90bbb95..217247d 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -416,7 +416,7 @@
 	fprintf(stderr,
 		"Usage : %s [-f <cfgfile>]* [ -vdV"
 		"D ] [ -n <maxconn> ] [ -N <maxpconn> ]\n"
-		"        [ -p <pidfile> ] [ -m <max megs> ] [ -C <dir> ]\n"
+		"        [ -p <pidfile> ] [ -m <max megs> ] [ -C <dir> ] [-- <cfgfile>*]\n"
 		"        -v displays version ; -vv shows known build options.\n"
 		"        -d enters debug mode ; -db only disables background mode.\n"
 		"        -dM[<byte>] poisons memory with <byte> (defaults to 0x50)\n"
@@ -702,6 +702,21 @@
 					nb_oldpids++;
 				}
 			}
+			else if (flag[0] == '-' && flag[1] == 0) { /* "--" */
+				/* now that's a cfgfile list */
+				argv++; argc--;
+				while (argc > 0) {
+					wl = (struct wordlist *)calloc(1, sizeof(*wl));
+					if (!wl) {
+						Alert("Cannot load configuration file %s : out of memory.\n", *argv);
+						exit(1);
+					}
+					wl->s = *argv;
+					LIST_ADDQ(&cfg_cfgfiles, &wl->list);
+					argv++; argc--;
+				}
+				break;
+			}
 			else { /* >=2 args */
 				argv++; argc--;
 				if (argc == 0)