MINOR: global: define MODE_STOPPING

Define a new mode MODE_STOPPING. It is used to indicate that the process
is in the stopping stage and no event loop runs anymore.

include/haproxy/global-t.h

@@ -39,6 +39,7 @@
 #define	MODE_ZERO_WARNING       0x200    /* warnings cause a failure */
 #define	MODE_DIAG	0x400   /* extra warnings */
 #define	MODE_CHECK_CONDITION	0x800    /* -cc mode */
+#define	MODE_STOPPING   0x1000  /* the process is in the deinit phase, the event loop is not running anymore. */
 
 /* list of last checks to perform, depending on config options */
 #define LSTCHK_CAP_BIND	0x00000001	/* check that we can bind to any port */

src/haproxy.c

@@ -2595,6 +2595,7 @@ void deinit(void)
 
 __attribute__((noreturn)) void deinit_and_exit(int status)
 {
+	global.mode |= MODE_STOPPING;
 	deinit();
 	exit(status);
 }