Add ha_federated.cc to libmysqld/Makefile.am so that configuring with both

embedded server and federated storage engine compiles. (Bug #7920)

libmysqld/Makefile.am

@@ -42,7 +42,7 @@ sqlexamplessources =	ha_example.cc ha_archive.cc ha_tina.cc
 noinst_HEADERS =	embedded_priv.h emb_qcache.h
 
 sqlsources = derror.cc field.cc field_conv.cc strfunc.cc filesort.cc \
-	ha_innodb.cc ha_berkeley.cc ha_heap.cc \
+	ha_innodb.cc ha_berkeley.cc ha_heap.cc ha_federated.cc \
 	ha_myisam.cc ha_myisammrg.cc handler.cc sql_handler.cc \
 	hostname.cc init.cc password.c \
 	item.cc item_buff.cc item_cmpfunc.cc item_create.cc \