Fix configure error regarding find_package which cannot find qmsetup

[fragoulin]

When using a mxe toolchain, the following error appears:

CMake Error at build/win64/_deps/windowkit-src/CMakeLists.txt:133 (find_package):
  Could not find a package configuration file provided by "qmsetup" with any
  of the following names:

    qmsetupConfig.cmake
    qmsetup-config.cmake

  Add the installation prefix of "qmsetup" to CMAKE_PREFIX_PATH or set
  "qmsetup_DIR" to a directory containing one of the above files.  If
  "qmsetup" provides a separate development package or SDK, be sure it has
  been installed.

This fix simply sets the qmsetup_DIR variable before the call to find_package.

Related to #195

[wangwenx190]

Thanks for your contribution! Sorry for the long delay due to we are quite busy recently.

[wangwenx190]

The issue is strange, can you provide a minimal reproduce example? How do you trigger this issue?

[fragoulin]

Sorry for the lack of information.
This issue occurs with a MXE toolchain. I use it for easily cross-compiling my QT projects using the cmake integration.

You first have to install MXE and build required QT6 packages for x86_64-w64-mingw32.static target:

1. Install MXE requirements
2. Install MXE
   git clone https://github.com/mxe/mxe.git
3. Build QT6 for x86_64-w64-mingw32.static target

cd mxe
make qt6-qtbase qt6-qtdeclarative -j 8 MXE_TARGETS='x86_64-w64-mingw32.static'

4. Update path to MXE usr/bin directory
   export PATH=/where MXE is installed/usr/bin:$PATH

Then compile qwindowkit using cmake integration from MXE for x86_64-w64-mingw32.static target:

cd qwindowkit
x86_64-w64-mingw32.static-cmake -S . -B build_x86_64-w64-mingw32.static \
  -DCMAKE_PREFIX_PATH=<where-MXE-is-installed>/usr/x86_64-w64-mingw32.static/qt6 \
  -DCMAKE_INSTALL_PREFIX=/opt/qwindowkit_x86_64-w64-mingw32.static \
  -DQWINDOWKIT_BUILD_WIDGETS=ON \
  -DQWINDOWKIT_BUILD_QUICK=ON \
  -DWIN32=1

The error message appears during installation of qmsetup :

...
-- Installing qmsetup (Release)...
CMake Error at CMakeLists.txt:128 (find_package):
  Could not find a package configuration file provided by "qmsetup" with any
  of the following names:

    qmsetupConfig.cmake
    qmsetup-config.cmake

  Add the installation prefix of "qmsetup" to CMAKE_PREFIX_PATH or set
  "qmsetup_DIR" to a directory containing one of the above files.  If
  "qmsetup" provides a separate development package or SDK, be sure it has
  been installed.