CLEANUP: muxes: remove useless inclusion of ebmbtree.h

Since 2.7 with commit 8522348482 ("BUG/MAJOR: conn-idle: fix hash indexing
issues on idle conns"), we've been using eb64 trees and not ebmb trees
anymore, and later we dropped all that to centralize the operations in
the server. Let's remove the ebmbtree.h includes from the muxes that do
not use them.

src/mux_fcgi.c

@@ -12,7 +12,6 @@
 
 #include <import/ist.h>
 #include <import/eb32tree.h>
-#include <import/ebmbtree.h>
 
 #include <haproxy/api.h>
 #include <haproxy/cfgparse.h>

src/mux_h1.c

@@ -10,7 +10,6 @@
  *
  */
 #include <import/ebistree.h>
-#include <import/ebmbtree.h>
 
 #include <haproxy/api.h>
 #include <haproxy/cfgparse.h>

src/mux_h2.c

@@ -11,7 +11,6 @@
  */
 
 #include <import/eb32tree.h>
-#include <import/ebmbtree.h>
 #include <haproxy/api.h>
 #include <haproxy/cfgparse.h>
 #include <haproxy/connection.h>

src/mux_spop.c

@@ -2,7 +2,6 @@
 
 #include <import/ist.h>
 #include <import/eb32tree.h>
-#include <import/ebmbtree.h>
 
 #include <haproxy/api.h>
 #include <haproxy/cfgparse.h>