Should be "fixed" in SVN r7030. Among other things, SDL=2 is "hard coded" now for MinGW builds (that is, you can no longer overwrite it).

Also, there is no option called "MINGW" since several versions because of a conflict with an environment variable of the same name used by the build tools themselves. It has been renamed to FORCE_MINGW, but you actually shouldn't need to specify that, it's auto-detected.

A mind is like a parachute. It doesn't work unless it's open. [Frank Zappa]