CMake: remove unnecessary `WITH_TIFF` and `IF()`

...Not sure to have done it in a clean way (between your commits & suggest resulting "dirty" merge https://github.com/OSGeo/libgeotiff/pull/123/commits/36e5a2b8ddbea6bed2a21621ea3fff282efd7035) but I double checked and

all the 3 points resolved
find package validated

final build clean and complete

cmake -LAH
-DCMAKE_FIND_DEBUG_MODE=1
-DCMAKE_CXX_FLAGS_INIT=/std:c++latest
-DCMAKE_C_FLAGS_INIT=/std:clatest
-DCMAKE_PREFIX_PATH=C:\sdk\release\vs17_x64-avx2;C:\sdk\release\vs17_x64-avx2\_openssl\openssl;C:\sdk\release\vs17_x64-avx2\_gdal;C:\sdk\release\vs17_x64-avx2\_proj;B:\serveur\mysql
-DCMAKE_FIND_USE_CMAKE_PATH=ON
-DCMAKE_FIND_USE_CMAKE_ENVIRONMENT_PATH=OFF
-DCMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH=ON
-DCMAKE_FIND_USE_CMAKE_SYSTEM_PATH=OFF
-DCMAKE_FIND_USE_INSTALL_PREFIX=OFF
-DCMAKE_BUILD_TYPE=RelWithDebInfo -G "Ninja"
-DCMAKE_INSTALL_PREFIX=C:\sdk\release\vs17_x64-avx2
-DBUILD_SHARED_LIBS=ON
-DWITH_UTILITIES=OFF
-DWITH_TOWGS84=ON
-DBUILD_DOC=OFF
-DBUILD_MAN=OFF
-DINTERFACE_LIB_PREFIX= C:\sdk\src\libgeotiff\libgeotiff

result

# libgeotiff git commit:36e5a2b
-- The C compiler identification is MSVC 19.40.33811.0
-- The CXX compiler identification is MSVC 19.40.33811.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/sdk/softs/vs22/Community/VC/Tools/MSVC/14.40.33807/bin/Hostx64/x64/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/sdk/softs/vs22/Community/VC/Tools/MSVC/14.40.33807/bin/Hostx64/x64/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for include file strings.h
-- Looking for include file strings.h - not found
-- Generating geo_config.h header
-- Generating geo_config.h header - done
-- Found PROJ: C:/sdk/release/vs17_x64-avx2/_proj/lib/proj.lib (found version "9.4.1")
-- Found TIFF: C:/sdk/release/vs17_x64-avx2/lib/cmake/tiff (found version "4.6.0")
-- Looking for TIFFOpen
-- Looking for TIFFOpen - found
--
################################
Summary of build options:
Build shared library:     ON
Build man pages:          OFF
Build doc files:          OFF
Build GeoTIFF utilities:  OFF
PROJ version:             9.4.1
TIFF version:             4.6.0
Build TOWGS84 support:    ON
################################
-- Configuring done (1.5s)
-- Generating done (0.0s)
-- Build files have been written to: C:/sdk/build/vs17_x64-avx2/libgeotiff
[1/17] Building C object CMakeFiles\geotiff_library.dir\geo_extra.c.obj
[2/17] Building C object CMakeFiles\geotiff_library.dir\geo_free.c.obj
[3/17] Building C object CMakeFiles\geotiff_library.dir\geo_print.c.obj
[4/17] Building C object CMakeFiles\geotiff_library.dir\geo_get.c.obj
[5/17] Building C object CMakeFiles\geotiff_library.dir\cpl_serv.c.obj
[6/17] Building C object CMakeFiles\geotiff_library.dir\geo_set.c.obj
[7/17] Building C object CMakeFiles\geotiff_library.dir\libxtiff\xtiff.c.obj
[8/17] Building C object CMakeFiles\geotiff_library.dir\geo_simpletags.c.obj
[9/17] Building C object CMakeFiles\geotiff_library.dir\geo_new.c.obj
[10/17] Building C object CMakeFiles\geotiff_library.dir\geo_trans.c.obj
[11/17] Building C object CMakeFiles\geotiff_library.dir\geo_tiffp.c.obj
[12/17] Building C object CMakeFiles\geotiff_library.dir\geo_write.c.obj
[13/17] Building C object CMakeFiles\geotiff_library.dir\geotiff_proj4.c.obj
[14/17] Building C object CMakeFiles\geotiff_library.dir\geo_normalize.c.obj
[15/17] Building C object CMakeFiles\geotiff_library.dir\geo_names.c.obj
[16/17] Linking C shared library bin\geotiff.dll
[16/17] Install the project...
-- Install configuration: "RelWithDebInfo"
-- Installing: C:/sdk/release/vs17_x64-avx2/include/geotiff.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geotiffio.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geovalues.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geonames.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geokeys.h
-- Installing: C:/sdk/release/vs17_x64-avx2/include/geo_config.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geo_tiffp.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geo_keyp.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geo_normalize.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/cpl_serv.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geo_simpletags.h
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_datum.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_gcs.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_pm.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_units.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geo_ctrans.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_ellipse.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_pcs.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_proj.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/epsg_vertcs.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geokeys.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/geokeys_v1_1.inc
-- Up-to-date: C:/sdk/release/vs17_x64-avx2/include/xtiffio.h
-- Installing: C:/sdk/release/vs17_x64-avx2/lib/geotiff.lib
-- Installing: C:/sdk/release/vs17_x64-avx2/bin/geotiff.dll
-- Installing: C:/sdk/release/vs17_x64-avx2/bin/geotiff.pdb
-- Installing: C:/sdk/release/vs17_x64-avx2/lib/pkgconfig/libgeotiff.pc
-- Installing: C:/sdk/release/vs17_x64-avx2/cmake/geotiff-config.cmake
-- Installing: C:/sdk/release/vs17_x64-avx2/cmake/geotiff-config-version.cmake
-- Installing: C:/sdk/release/vs17_x64-avx2/cmake/geotiff-depends.cmake
-- Installing: C:/sdk/release/vs17_x64-avx2/cmake/geotiff-depends-relwithdebinfo.cmake
[version] '1.7.4' C:\sdk\release\vs17_x64-avx2\bin\geotiff.dll (C:\sdk\release\vs17_x64-avx2\include\geotiff.h)

OSGeo / libgeotiff

CMake: remove unnecessary `WITH_TIFF` and `IF()` #123