Add ruleutils file for PostgreSQL 11

.gitattributes

@@ -28,4 +28,5 @@ configure				-whitespace
 src/backend/distributed/utils/citus_outfuncs.c -citus-style
 src/backend/distributed/utils/ruleutils_96.c -citus-style
 src/backend/distributed/utils/ruleutils_10.c -citus-style
+src/backend/distributed/utils/ruleutils_11.c -citus-style
 src/include/distributed/citus_nodes.h -citus-style

src/backend/distributed/utils/ruleutils_10.c

@@ -17,7 +17,7 @@
 
 #include "postgres.h"
 
-#if (PG_VERSION_NUM >= 100000)
+#if (PG_VERSION_NUM >= 100000 && PG_VERSION_NUM < 110000)
 
 #include <ctype.h>
 #include <unistd.h>
@@ -7905,4 +7905,4 @@ get_range_partbound_string(List *bound_datums)
 	return buf->data;
 }
 
-#endif /* (PG_VERSION_NUM >= 100000) */
+#endif /* (PG_VERSION_NUM >= 100000 && PG_VERSION_NUM < 110000) */