Bug#22834591: unused-local-typedef warnings from boost 1.59

Build broken when all -DWITH_XXX=system

cmake .. -DWITH_EDITLINE=system -DWITH_LIBEVENT=system -DWITH_LZ4=system -DWITH_MECAB=system -DWITH_SSL=system -DWITH_ZLIB=system

CMake Error at plugin/keyring/CMakeLists.txt:53 (ADD_COMPILE_FLAGS):
  Unknown CMake command "ADD_COMPILE_FLAGS".

Fix:
INCLUDE(${MYSQL_CMAKE_SCRIPT_DIR}/compile_flags.cmake)

(cherry picked from commit 70b6d76899732daf96da1f02777e4049dc2a6bca)

Author: Tor Didriksen

plugin/keyring/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,6 +13,8 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
+INCLUDE(${MYSQL_CMAKE_SCRIPT_DIR}/compile_flags.cmake)
+
 INCLUDE_DIRECTORIES(${BOOST_PATCHES_DIR} ${BOOST_INCLUDE_DIR})
 INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}/common)