MinGW - Minimalist GNU for Windows

This is an improved patch for propagating Ctrl-C/Ctrl-Break events from
MSYS to regular Windows apps. It was originally posted here
http://thread.gmane.org/gmane.comp.gnu.mingw.msys/3793/focus=3797
This patch also supersedes
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=1333217&group_
id=2435

This code assumes that the target program has been linked with an MSVC
CRT DLL. If it can find one of these DLLs attached to the target, then
it will find the raise() entry point in the DLL, and use that to send
signals to the target. One advantage of this approach is that it will
work even if the target program doesn't use a Console. The obvious
disadvantage is that it's pretty invasive. If there's no MSVCRT, then it
does nothing.