* [boost] Update to 1.71.0

* [openmvs] Fixes for boost 1.71

* [telnetpp] DISABLE_PARALLEL_CONFIGURE

* [execute_process] Fix output variables (like error_code) not getting populated

* [telnetpp] Add missing boost-exception dependency

* [boost] Refactor generate-ports.ps1 into scripts dir. Enable boost-thread on uwp.

* [boost-iostreams] Revert removal of zstd dependency

* [openmvs] Fix tools deployment

CMAKE_CURRENT_LIST_DIR reflect current directory. Thus It can be lowercase drive letter.
The lowercase drive letter cause #8237 issue.
Fixup drive letter to uppercase by using get_filename_component().

CMAKE_TRY_COMPILE_PLATFORM_VARIABLES is used when CMake 3.6.0 or higher
is encountered. For older versions the previous behavior emulating this
functionality is used.

* forward extra arguments to vcpkg_configure_qmake from submodules
* make image format dependent on tiff and libwebp
* make tools dependent on imageformat
* build options must be passed a bit different then normal qmake options
* add the required dependencies
* a new dependency discovered in qt5-declarative
* need webpdemux also
* qt5-declarative is dependent on imageformats so we can drop it here
* remove empty qt.conf if it exists. closes #8180
* add all recommended dependencies as dependencies in control.

* [vcpkg] add missing implib definitions, fix shared lib extension on mac

(cherry picked from commit 2cddef9541202ecc01ad43036575bc606dc01117)

* Better find_library suffixes and prefixes.

* moved additional suffix into a comment and reverted back to what is expected on windows

* updated documentation for add variables.

* - Added scripts variable to ports file.
- Added check if triplet file is not available (NPE).

* - Fixed line endings.

* Provide location of .vcpkg-root to ports.cmake

* vcpkg sets VCPKG_ROOT_PATH in ports.cmake

* [vcpkg] Fail if VCPKG_ROOT_PATH is not passed from vcpkg.exe

* [vcpkg] Fix vcpkg rooth path

* [vcpkg] Make --x-scripts-root an experimental command

* update to 5.12.4
* removed port qt5-modularscripts and split it functionality into more functions into qt5-base
* added qt_port_hashes.cmake for simpler upgrade.
* added optional VCPKG_QT_HOST_MKSPEC and VCPKG_QT_TARGET_MKSPEC to select QTs build mkspecs from a triplet
* qt_<config>.conf are now copied from the build dir instead from the port dir
* fixed freetype dependencies.
* cleanup of vcpkg_qmake scripts. No strange/unclear replacements anymore.
* introduced vcpkg_buildpath_length_warning
* changed directory layout of the qt5 installation executables and mkspecs a bit.

In Powershell 6.2/7.0, `Get-ChildItem`'s paths are now printed as
absolute paths instead of relative paths; this breaks the code we have
that assumes that they're printed as relative paths.

Thus, change the code to request the `Name` property specifically, which
is what we actually wanted.