Fix up missing WITHOUT_DOCS, WITHOUT_CLIENT options

--- extra/CMakeLists.txt.orig	2015-10-15 15:43:36 UTC
+++ extra/CMakeLists.txt
@@ -100,6 +100,8 @@ 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()
+ENDIF()