cmake CXX_HAVE_DEPRECATED_DECLARATIONS examples

mysql/mysql-router src/routing/CMakeLists.txt :75 

check_cxx_compiler_flag("-Wdeprecated-declarations" CXX_HAVE_DEPRECATED_DECLARATIONS)

mysql/mysql-router src/routing/tests/CMakeLists.txt :55 

check_cxx_compiler_flag("-Wdeprecated-declarations" CXX_HAVE_DEPRECATED_DECLARATIONS)

mysql/mysql-router src/x_protocol/CMakeLists.txt :80 

check_cxx_compiler_flag("-Wdeprecated-declarations" CXX_HAVE_DEPRECATED_DECLARATIONS)