REORG: mworker: declare master variable in global.h

This variable is used at several places, better declare it in global.h.
diff --git a/include/types/global.h b/include/types/global.h
index 74ebf14..0d1c4e2 100644
--- a/include/types/global.h
+++ b/include/types/global.h
@@ -219,6 +219,7 @@
 extern volatile unsigned long sleeping_thread_mask;
 extern struct list proc_list; /* list of process in mworker mode */
 extern struct mworker_proc *proc_self; /* process structure of current process */
+extern int master; /* 1 if in master, 0 otherwise */
 
 /* bit values to go with "warned" above */
 #define WARN_BLOCK_DEPRECATED       0x00000001
diff --git a/src/cli.c b/src/cli.c
index b8b2335..43dc8b3 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -95,8 +95,6 @@
 
 extern const char *stat_status_codes[];
 
-extern int master;
-
 static struct proxy *mworker_proxy; /* CLI proxy of the master */
 
 static char *cli_gen_usage_msg(struct appctx *appctx)
diff --git a/src/listener.c b/src/listener.c
index 4bcf2d8..c75f8ef 100644
--- a/src/listener.c
+++ b/src/listener.c
@@ -50,8 +50,6 @@
 	.list = LIST_HEAD_INIT(bind_keywords.list)
 };
 
-extern int master;
-
 struct xfer_sock_list *xfer_sock_list = NULL;
 
 /* This function adds the specified listener's file descriptor to the polling