[Debian-med-packaging] Bug#1000222: orthanc force gnuc++11 reason

[Mathieu Malaterre]

Control: tags -1 upstream confirmed
Control: affects -1 dcmtk/3.6.6-2

For some reason orthanc forces the uses of gnuc++11 gcc compiler flag.
Unless there is a good reason, I would simply suggest to remove this
hard-coded value:

 % grep -r gnu++11 .
./OrthancFramework/Resources/CMake/DownloadOrthancFramework.cmake:
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")
./OrthancFramework/Resources/CMake/JsonCppConfiguration.cmake:
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")
./OrthancFramework/UnitTestsSources/CMakeLists.txt:
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")