Revert CMakeLists.txt mistake for mmaps_generator

this revert https://github.com/TrinityCore/TrinityCore/commit/401527c351a7dee7768b70ca5e73bde52f9b2977
because when I select "tools" in cmake, mmaps_generator isn't in project and cant compile
delete "#" too for both meshextractor and mmaps_generator - revert https://github.com/TrinityCore/TrinityCore/commit/ad8c046916262918b88917cbe4194a943ce75d16#diff-31