REORG: include: move backend.h to haproxy/backend{,-t}.h

The files remained mostly unchanged since they were OK. However, half of
the users didn't need to include them, and about as many actually needed
to have it and used to find functions like srv_currently_usable() through
a long chain that broke when moving the file.
diff --git a/include/types/backend.h b/include/haproxy/backend-t.h
similarity index 97%
rename from include/types/backend.h
rename to include/haproxy/backend-t.h
index 120081f..757bb2f 100644
--- a/include/types/backend.h
+++ b/include/haproxy/backend-t.h
@@ -1,5 +1,5 @@
 /*
- * include/types/backend.h
+ * include/haproxy/backend-t.h
  * This file assembles definitions for backends
  *
  * Copyright (C) 2000-2012 Willy Tarreau - w@1wt.eu
@@ -19,17 +19,16 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#ifndef _TYPES_BACKEND_H
-#define _TYPES_BACKEND_H
+#ifndef _HAPROXY_BACKEND_T_H
+#define _HAPROXY_BACKEND_T_H
 
 #include <haproxy/lb_chash-t.h>
 #include <haproxy/lb_fas-t.h>
 #include <haproxy/lb_fwlc-t.h>
 #include <haproxy/lb_fwrr-t.h>
 #include <haproxy/lb_map-t.h>
+#include <haproxy/thread-t.h>
 #include <haproxy/api-t.h>
-#include <haproxy/thread.h>
-
 #include <types/server.h>
 
 /* Parameters for lbprm.algo */
@@ -168,7 +167,7 @@
 	void (*server_drop_conn)(struct server *);       /* to be called when connection is dropped */
 };
 
-#endif /* _TYPES_BACKEND_H */
+#endif /* _HAPROXY_BACKEND_T_H */
 
 /*
  * Local variables:
diff --git a/include/proto/backend.h b/include/haproxy/backend.h
similarity index 96%
rename from include/proto/backend.h
rename to include/haproxy/backend.h
index 57d606e..6662d59 100644
--- a/include/proto/backend.h
+++ b/include/haproxy/backend.h
@@ -1,5 +1,5 @@
 /*
- * include/proto/backend.h
+ * include/haproxy/backend.h
  * Functions prototypes for the backend.
  *
  * Copyright (C) 2000-2012 Willy Tarreau - w@1wt.eu
@@ -19,14 +19,13 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#ifndef _PROTO_BACKEND_H
-#define _PROTO_BACKEND_H
+#ifndef _HAPROXY_BACKEND_H
+#define _HAPROXY_BACKEND_H
 
+#include <haproxy/backend-t.h>
 #include <haproxy/api.h>
 #include <haproxy/proxy-t.h>
 #include <haproxy/time.h>
-
-#include <types/backend.h>
 #include <types/server.h>
 #include <types/stream.h>
 
@@ -144,7 +143,7 @@
  */
 void set_backend_down(struct proxy *be);
 
-#endif /* _PROTO_BACKEND_H */
+#endif /* _HAPROXY_BACKEND_H */
 
 /*
  * Local variables:
diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index d66ab34..b89fb21 100644
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -31,6 +31,7 @@
 #include <import/ebpttree.h>
 
 #include <haproxy/arg-t.h>
+#include <haproxy/backend-t.h>
 #include <haproxy/check-t.h>
 #include <haproxy/counters-t.h>
 #include <haproxy/freq_ctr-t.h>
@@ -38,7 +39,6 @@
 #include <haproxy/obj_type-t.h>
 #include <haproxy/thread-t.h>
 #include <haproxy/api-t.h>
-#include <types/backend.h>
 #include <types/server.h>
 
 /* values for proxy->state */
diff --git a/include/proto/queue.h b/include/proto/queue.h
index 735a1f1..cd4c5ca 100644
--- a/include/proto/queue.h
+++ b/include/proto/queue.h
@@ -22,6 +22,7 @@
 #ifndef _PROTO_QUEUE_H
 #define _PROTO_QUEUE_H
 
+#include <haproxy/backend.h>
 #include <haproxy/api.h>
 #include <haproxy/pool.h>
 #include <haproxy/proxy-t.h>
@@ -30,8 +31,6 @@
 #include <types/stream.h>
 #include <types/server.h>
 
-#include <proto/backend.h>
-
 extern struct pool_head *pool_head_pendconn;
 
 struct pendconn *pendconn_add(struct stream *strm);