CLEANUP: include: tree-wide alphabetical sort of include files

This patch fixes all the leftovers from the include cleanup campaign. There
were not that many (~400 entries in ~150 files) but it was definitely worth
doing it as it revealed a few duplicates.
diff --git a/src/lb_fwrr.c b/src/lb_fwrr.c
index 6183433..05ae5f6 100644
--- a/src/lb_fwrr.c
+++ b/src/lb_fwrr.c
@@ -11,8 +11,8 @@
  */
 
 #include <import/eb32tree.h>
-#include <haproxy/backend.h>
 #include <haproxy/api.h>
+#include <haproxy/backend.h>
 #include <haproxy/queue.h>
 #include <haproxy/server-t.h>