COMP: update internal vxl for clang compilation

Utilities/ITK/Utilities/vxl/CMakeLists.txt

.../config/cmake/DSPTemplates/mex/CMakeSystemConfig.cmake.in

.../config/cmake/DSPTemplates/with_mfc/DLLHeader.dsptemplate

.../config/cmake/DSPTemplates/with_mfc/EXEHeader.dsptemplate

...fig/cmake/DSPTemplates/with_mfc/UtilityHeader.dsptemplate

.../ITK/Utilities/vxl/config/cmake/Modules/CTestCustom.cmake

.../ITK/Utilities/vxl/config/cmake/Modules/FindGEOTIFF.cmake

...ies/ITK/Utilities/vxl/config/cmake/Modules/FindJPEG.cmake

...es/ITK/Utilities/vxl/config/cmake/Modules/FindMPEG2.cmake

...TK/Utilities/vxl/config/cmake/Modules/FindOpenJPEG2.cmake

...ties/ITK/Utilities/vxl/config/cmake/Modules/FindPNG.cmake

...ies/ITK/Utilities/vxl/config/cmake/Modules/FindTIFF.cmake

...ies/ITK/Utilities/vxl/config/cmake/Modules/FindZLIB.cmake

...lities/vxl/config/cmake/Modules/NewCMake/FindCoin3D.cmake

...lities/vxl/config/cmake/Modules/NewCMake/FindDC1394.cmake

...ilities/vxl/config/cmake/Modules/NewCMake/FindDCMTK.cmake

...es/vxl/config/cmake/Modules/NewCMake/FindDirectShow.cmake

...Utilities/vxl/config/cmake/Modules/NewCMake/FindECW.cmake

...lities/vxl/config/cmake/Modules/NewCMake/FindFFMPEG.cmake

...ities/vxl/config/cmake/Modules/NewCMake/FindGEOTIFF.cmake