btl: fix rcache rewrite merge error

Signed-off-by: Nathan Hjelm <hjelmn@me.com>

Author: hjelmn

opal/mca/btl/btl.h

@@ -122,6 +122,7 @@
 #include "opal/datatype/opal_convertor.h"
 #include "opal/mca/mca.h"
 #include "opal/mca/mpool/mpool.h"
+#include "opal/mca/rcache/rcache.h"
 
 BEGIN_C_DECLS
 
@@ -132,7 +133,6 @@ BEGIN_C_DECLS
 struct mca_btl_base_module_t;
 struct mca_btl_base_endpoint_t;
 struct mca_btl_base_descriptor_t;
-struct mca_mpool_base_resources_t;
 struct opal_proc_t;
 
 /**