Check if USE_STD_CXX_INCLUDES is still needed
USE_STD_CXX_INCLUDES checks whether specific C++ standard library's headers are there, in order to include the C alternatives otherwise. Apart from a usage incosistency (see bug #762) it is not clear whether the macro and the related configure test are still needed: Every compiler supporting C++-98 must offer those headers.
Actually, DCMTK's current CMake build scripts set this macro hard-wired to 1 and so far no problems showed up an CMake-enabled systems (thus to check: QNX, SUNpro, ... which on build with autoconf?).