Fix up missing WITHOUT_DOCS, WITHOUT_CLIENT options

--- extra/CMakeLists.txt.orig	2017-05-14 23:13:15 UTC
+++ extra/CMakeLists.txt
@@ -96,9 +96,11 @@ IF(UNIX)
   MYSQL_ADD_EXECUTABLE(resolve_stack_dump resolve_stack_dump.c)
   TARGET_LINK_LIBRARIES(resolve_stack_dump mysys)
 
+IF(FALSE)
   MYSQL_ADD_EXECUTABLE(mysql_waitpid mysql_waitpid.c COMPONENT Client)
   TARGET_LINK_LIBRARIES(mysql_waitpid mysys)
+ENDIF()

   MYSQL_ADD_EXECUTABLE(mysqld_safe_helper mysqld_safe_helper.c COMPONENT Server)
   TARGET_LINK_LIBRARIES(mysqld_safe_helper mysys)
 ENDIF()