MEDIUM: proxy: replace proxy->state with proxy->disabled

The remaining proxy states were only used to distinguish an enabled
proxy from a disabled one. Due to the initialization order, both
PR_STNEW and PR_STREADY were equivalent after startup, and they
would only differ from PR_STSTOPPED when the proxy is disabled or
shutdown (which is effectively another way to disable it).

Now we just have a "disabled" field which allows to distinguish them.
It's becoming obvious that start_proxies() is only used to print a
greeting message now, that we'd rather get rid of. Probably that
zombify_proxy() and stop_proxy() should be merged once their
differences move to the right place.
diff --git a/include/haproxy/backend.h b/include/haproxy/backend.h
index f6b25e7..8a763bf 100644
--- a/include/haproxy/backend.h
+++ b/include/haproxy/backend.h
@@ -52,7 +52,7 @@
 /* Returns number of usable servers in backend */
 static inline int be_usable_srv(struct proxy *be)
 {
-        if (be->state == PR_STSTOPPED)
+        if (be->disabled)
                 return 0;
         else if (be->srv_act)
                 return be->srv_act;
diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index aa8038d..a17537a 100644
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -42,13 +42,6 @@
 #include <haproxy/thread-t.h>
 #include <haproxy/uri_auth-t.h>
 
-/* values for proxy->state */
-enum pr_state {
-	PR_STNEW = 0,           /* proxy has not been initialized yet */
-	PR_STREADY,             /* proxy has been initialized and is ready */
-	PR_STSTOPPED,           /* proxy is stopped (end of a restart) */
-} __attribute__((packed));
-
 /* values for proxy->mode */
 enum pr_mode {
 	PR_MODE_TCP = 0,
@@ -252,7 +245,7 @@
 
 struct proxy {
 	enum obj_type obj_type;                 /* object type == OBJ_TYPE_PROXY */
-	enum pr_state state;                    /* proxy state, one of PR_* */
+	char disabled;                          /* non-zero if disabled or shutdown */
 	enum pr_mode mode;                      /* mode = PR_MODE_TCP, PR_MODE_HTTP or PR_MODE_HEALTH */
 	char cap;                               /* supported capabilities (PR_CAP_*) */
 	unsigned int maxconn;                   /* max # of active streams on the frontend */