/* roll our own strcasecmp and strncasecmp for Win */

MinGW has its own implementations of strcasecmp, strncasecmp and strdup (in string.h) - maybe (some) MS compilers don't.
Anyway, just change the #idef _WIN32 (a coupla lines higher up, at about line 102) to #ifdef _MSC_VER.
Then, in supportrev.c there's a section defining those three functions that also begins with an #ifdef _WIN32. You'll need to change it to #ifdef _MSC_VER too.

See how that goes.

Cheers,
Rob