I don't remember but when you install couple of programs during life-time of your computer sometimes appearing files which I don't know where they came from. So the MSVCRTD.DLL was included in this way. First was the idea that I need it. Next step the MinGW runtime nor GCC does not support its linking. Changed the MinGW run-time and also made different spec file for GCC. If you start using MSVCRTD.DLL you cannot mix memory allocations without D. It corrupts the heap and then you get some kind of assertion message from run-time library. But despite of these things it is very useful. There was an idea at first time to share it but it possible only through MinGW integration. I'm not sure if it can work consistently by only copying some file to your MinGW install. But I don't understand why there in FSF don't add the MSVCRTD.DLL linking by default when you are using -g switch on the command line. If you want I can make compressed package (e.g. ZIP or similar) and share it through my website without MSVCRTD.DLL. I don't know if it is legal to share it.
Among other things I made this: (see attached file)
To make easily to switch between build configurations. Somewhere in this forum I mention about it but don't got any positive response for such change of compiler plugin.