[qt5-tools] Fix build fail with mingw

[uwyc]

Fixes #32689.

Fixes package Qt5UiPlugin was not found in the pkg-config search path.

-- Using source at C:/Src/vcpkg/buildtrees/qt5-tools/src/5.15.10-453af505a4
-- Getting CMake variables for x64-mingw-dynamic
-- Using cached mingw-w64-i686-pkgconf-1~1.8.0-2-any.pkg.tar.zst.
-- Using cached msys2-msys2-runtime-3.4.6-1-x86_64.pkg.tar.zst.
-- Using msys root at D:/Data/vcpkg-downloads/tools/msys2/6f3fa1a12ef85a6f
-- Configuring x64-mingw-dynamic-rel
-- Configuring x64-mingw-dynamic-rel done
-- Configuring x64-mingw-dynamic-dbg
-- Configuring x64-mingw-dynamic-dbg done
-- Package build-x64-mingw-dynamic-dbg
-- Package build-x64-mingw-dynamic-rel
-- Package install-x64-mingw-dynamic-dbg
-- Package install-x64-mingw-dynamic-rel
-- Fixing pkgconfig file: C:/Src/vcpkg/packages/qt5-tools_x64-mingw-dynamic/lib/pkgconfig/Qt5Designer.pc
-- Fixing pkgconfig file: C:/Src/vcpkg/packages/qt5-tools_x64-mingw-dynamic/lib/pkgconfig/Qt5Help.pc
-- Fixing pkgconfig file: C:/Src/vcpkg/packages/qt5-tools_x64-mingw-dynamic/lib/pkgconfig/Qt5UiTools.pc
CMake Error at scripts/cmake/vcpkg_fixup_pkgconfig.cmake:141 (message):

  D:/Data/vcpkg-downloads/tools/msys2/6f3fa1a12ef85a6f/mingw32/bin/pkg-config.exe
  --exists Qt5Designer failed with error code: 1

      ENV{PKG_CONFIG_PATH}: "C:/Src/vcpkg/packages/qt5-tools_x64-mingw-dynamic/lib/pkgconfig;C:/Src/vcpkg/packages/qt5-tools_x64-mingw-dynamic/share/pkgconfig;C:/Src/vcpkg/installed/x64-mingw-dynamic/lib/pkgconfig;C:/Src/vcpkg/installed/x64-mingw-dynamic/share/pkgconfig"
      output: Package Qt5UiPlugin was not found in the pkg-config search path.

  Perhaps you should add the directory containing `Qt5UiPlugin.pc'

  to the PKG_CONFIG_PATH environment variable

  Package 'Qt5UiPlugin', required by 'Qt5Designer', not found
Call Stack (most recent call first):
  scripts/cmake/vcpkg_fixup_pkgconfig.cmake:206 (z_vcpkg_fixup_pkgconfig_check_files)
  installed/x64-mingw-dynamic/share/qt5/qt_build_submodule.cmake:21 (vcpkg_fixup_pkgconfig)
  installed/x64-mingw-dynamic/share/qt5/qt_submodule_installation.cmake:9 (qt_build_submodule)
  ports/qt5-tools/portfile.cmake:3 (qt_submodule_installation)
  scripts/ports.cmake:147 (include)

• Changes comply with the maintainer guide
• SHA512s are updated for each updated download
• The "supports" clause reflects platforms that may be fixed by this new version
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[uwyc]

@microsoft-github-policy-service agree

[BillyONeal]

Thanks!