Fix regression for Javadoc jar build (#12404)

Summary:
#12371 Introduced regression not defining dependency between `create_javadoc`  and `rocksdb_javadocs_jar` build targets.

Pull Request resolved: #12404

Reviewed By: pdillinger

Differential Revision: D54516862

Pulled By: ajkr

fbshipit-source-id: 785a99b2caf979395ae0de60e40e7d1b93059adb

java/CMakeLists.txt

@@ -808,6 +808,7 @@ add_custom_target(rocksdb_javadocs_jar ALL
   COMMAND ${Java_JAR_EXECUTABLE} cvf ${CMAKE_CURRENT_BINARY_DIR}/${ROCKSDB_JAVADOC_JAR} -C ${CMAKE_CURRENT_BINARY_DIR}/javadoc/rocksdb .
   BYPRODUCTS ${CMAKE_CURRENT_BINARY_DIR}/${ROCKSDB_JAVADOC_JAR}
   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+  DEPENDS rocksdb_javadoc
 )
 
 # Sources Jar