[NPS] Fixed NPS warnings on OS X

OS X uses clang to compile the code, thus we have a bit different
warning system. Now the C++ code is being compiled with the G++ clang
compiler instead of GCC.
Actually compile C++ files with CXX and C files with CC.

Also fixed some other warnings including UTF-16 character usage.
Converted config report warningt to PRINT_CONFIG_MSG.
We need to push the diagnostics first for clang.
Added GNU99 standard flag to the C targets.