cmake HAVE_SYSTEM_PCRE examples

rAthenaCN/rAthenaCN 3rdparty/pcre/CMakeLists.txt :62 

mark_as_advanced( HAVE_SYSTEM_PCRE )

rAthenaCN/rAthenaCN 3rdparty/pcre/CMakeLists.txt :64 

unset( HAVE_SYSTEM_PCRE CACHE )