CMake build support

[hummeltech]

This adds CMake build system support to mod_tile.

• Added macOS building & testing support
• Added FreeBSD building & testing support
• Integrated mod_tile.so tests from GitHub Actions into CMake/CTest configuration
  • Also added a test for /dirty and /status
  • They can now easily be run locally with ctest:

    $ ctest -T test
    Test project /__w/mod_tile/mod_tile/build
          Start  1: gen_tile_test
     1/11 Test  #1: gen_tile_test ....................   Passed    2.20 sec
          Start  2: create_dirs
     2/11 Test  #2: create_dirs ......................   Passed    0.00 sec
          Start  3: start_renderd
     3/11 Test  #3: start_renderd ....................   Passed    0.11 sec
          Start  4: start_httpd
     4/11 Test  #4: start_httpd ......................   Passed    0.04 sec
          Start  5: download_tile
     5/11 Test  #5: download_tile ....................   Passed    0.21 sec
          Start  6: check_tile
     6/11 Test  #6: check_tile .......................   Passed    0.00 sec
          Start  7: dirty_tile
     7/11 Test  #7: dirty_tile .......................   Passed   10.02 sec
          Start  8: remove_tile
     8/11 Test  #8: remove_tile ......................   Passed    0.00 sec
          Start  9: stop_renderd
     9/11 Test  #9: stop_renderd .....................   Passed    0.01 sec
          Start 10: stop_httpd
    10/11 Test #10: stop_httpd .......................   Passed    0.01 sec
          Start 11: clear_dirs
    11/11 Test #11: clear_dirs .......................   Passed    0.01 sec
    
    100% tests passed, 0 tests failed out of 11
    
    Total Test time (real) =  12.61 sec
    

• Coverage is now also supported when using CMake/CTest & gcc/g++
  • It can also easily be run locally with ctest (when built with CFLAGS/CXXFLAGS=--coverage):

    $ ctest -T coverage
    Performing coverage
       Processing coverage (each . represents one file):
        ..............................................
       Accumulating results (each . represents one file):
        ....................
            Covered LOC:         2653
            Not covered LOC:     3769
            Total LOC:           6422
            Percentage Coverage: 41.31%
    

• LLVM (clang) building & testing support has also been added
  • Supported on all Linux distributions, as well as FreeBSD & macOS