[4.3.4] Revert CMakeLists.txt mistake for mmaps

this revert 401527c
because when I select "tools" in cmake, mmaps_generator isn't in project and can't compile

i didnt select meshextractor, only tools in cmake
meshextractor have problem during compile with library
Merge pull request #11860 from msoky/patch-4

[4.3.4] Revert CMakeLists.txt mistake for mmaps