SDK installer shouldn't discard output from the "mingw-get" stage

[SamB]

I got some errors from the mingw-get stage of the SDK installation, but I can't easily report them because the window with the output insists on disappearing after everything is done.

(At least one of them is a 404 trying to download one of the packages.)

[sschuberth]

The installer already supports the /log-mingw-get=<file> option to log the output of mingw-get to a file, see how it is used here.

If the error is about wget like

mingw-get.exe: *** ERROR *** internal package specification error
mingw-get.exe: *** ERROR *** can't get 'tarname' for non-release element <<<unknown>>>
mingw-get.exe: *** ERROR *** please report this to the package maintainer
mingw-get.exe: *** ERROR *** wget-1.12-1-msys-1.0.13-bin.tar.lzma: requires...
mingw-get.exe: *** ERROR *** msys-libopenssl-*-msys-*-dll-100.tar: unresolved dependency (type 'eq')
mingw-get.exe: *** ERROR *** msys-libopenssl-*-msys-*-dll-100.tar: cannot identify any providing package
mingw-get.exe: *** ERROR *** please report this to the package maintainer

then it's already known. But it's not severe, just ignore it for now.