Enable in-package substitute of tr1/tuple

In clang 6.0 the tr1/tuple header is not present, and this cause a
compilation error inside of the gtest framework. However, if we set a
define, it will use its own substitute of tr1/tuple, which is sufficient
for the unit tests.

ApplicationCode/FileInterface/FileInterface_UnitTests/CMakeLists.txt

@@ -75,6 +75,10 @@ set( LINK_LIBRARIES
     ${QT_LIBRARIES}
 )
 
+if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+    set(CMAKE_CXX_FLAGS "-DGTEST_USE_OWN_TR1_TUPLE=1")
+endif()
+
 add_executable( ${ProjectName}
     ${CODE_HEADER_FILES}