[vcpkg baseline][many ports] Fix build error

[JackBoosY]

Fix baseline issues, these changes need to fix togather, since they affected each other in CI testing.

• wxwidgets
• mlpack
• embree2
• embree3
• opencv4
• zxing-cpp
• dbow2
• clamav

1. Fix wxwidgets bug:

F:\vcpkg\buildtrees\wxwidgets\x86-windows-dbg\libs\stc\cotire\wxscintilla_CXX_prefix.hxx(4): fatal error C1083: Cannot open include file: 'F:\vcpkg\buildtrees\wxwidgets\src\54f4f955a1-1de49a51d0\build\cmake\lib\stc\CONFIG': No such file or directory

It's becuase the parameter wxSCINTILLA_PREC_HEADER is empty:

if(wxBUILD_PRECOMP)
    # The auto-generated header causes undefined members and identifiers in the
    # standard c++ headers when using clang.
    # Do not disable precompiled headers entirely but use the main Scintilla
    # header as prefix header so there is at least a small speedup.
    if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
        set(wxSCINTILLA_PREC_HEADER "${wxSOURCE_DIR}/src/stc/scintilla/include/Scintilla.h")
    endif()
    wx_target_enable_precomp(wxscintilla ${wxSCINTILLA_PREC_HEADER})
endif()

causes the leaked field CONFIG to be set in set_target_properties in function wx_target_enable_precomp.
Then, get_property obtained the property and read its file path, resulting in the generation of the wrong wxscintilla_CXX_prefix.hxx:

/* cotire.cmake 1.8.0 generated file */
/* F:/vcpkg/buildtrees/wxwidgets/x86-windows-dbg/libs/stc/cotire/wxscintilla_CXX_prefix.hxx */
/* cotire.cmake 1.8.0 generated file */
/* F:/vcpkg/buildtrees/wxwidgets/x86-windows-dbg/libs/stc/cotire/wxscintilla_CXX_prefix.hxx */
#ifdef __cplusplus
#include "F:\vcpkg\buildtrees\wxwidgets\src\54f4f955a1-1de49a51d0\build\cmake\lib\stc\CONFIG"
#endif

which is not exist.

2. Fix mlpack configure bug, already fixed in upstream mlpack/mlpack@52e123e.

[JackBoosY]

@cenit When building opencv4:x86-windows or opencv4:x64-windows, we met an error message:

CMake Error at cmake/OpenCVGenConfig.cmake:49 (export):
  export Export set "OpenCVModules" not found.
Call Stack (most recent call first):
  CMakeLists.txt:923 (include)

And for opencv4:x64-linux:

The following empty directories were found:

    /home/usr/work/vcpkg/packages/opencv4_x64-linux/debug

If a directory should be populated but is not, this might indicate an error in the portfile.
If the directories are not needed and their creation cannot be disabled, use something like this in the portfile to remove them:

    file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/a/dir" "${CURRENT_PACKAGES_DIR}/some/other/dir")


Found 1 error(s). Please correct the portfile:
    /home/usr/work/vcpkg/ports/opencv4/portfile.cmake

Can you please take a look?

Thanks.

[PhoebeHui]

Fix embree2/embree3 CI test failures:

CMake Error in CMakeLists.txt:
  You have set CMAKE_BACKWARDS_COMPATIBILITY to a CMake version less than
  2.4.  This version of CMake only supports backwards compatibility with
  CMake 2.4 or later.  For compatibility with older versions please use any
  CMake 2.8.x release or lower.

Reference https://cmake.org/cmake/help/latest/policy/CMP0001.html#policy:CMP0001

[JackBoosY]

The opencv4 issue is OPENCV_MODULES_BUILD always be cleaned after insert items. At last, nothing to be built.
The dbow2 and zxing-cpp regressions are related to opencv4 regression.

[PhoebeHui]

The opencv4 failures start from b369b11.
Related PR #17955

cc @strega-nil

[cenit]

i saw few days ago that opencv is not even tested in many CI configs... i will take a look and send fixes asap (might take a couple of days, sorry)

[cenit]

yeah I can confirm anyway that in the last 24h OpenCV was broken for everybody here on vcpkg.
Again a PR was merged and that broke all my "bleeding edge" pipelines. They are really bleeding....

[cenit]

this is making the fix much more urgent also for me

[cenit]

#17991 will revert #17955 @JackBoosY

[JackBoosY]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[PhoebeHui]

@dan-shaw, could you help merge this PR?