SDL_crash -- fatal error catching with user callback

On Windows on x86 (it appears that x64 is going to be much more complicated, and I’m not sure anyone actually uses Itanium), I have rendered the code for dbghelp or imagehlp unnecessary, and thus it is only included if you define CRASH_DBGHELP. My next goal is, barring sudden access to a non-Windows platform, to do the same for x64.

This change has brought the size of the library back down to under 4kb, which pleased me greatly.------------------------
Nate Fries