[Mingw-cross-env-list] Qt suport for Debian kFreeBSD & DragonFly

[Tony Theodore]

Hi Mark,

I just pushed two changes adding Qt support for Debian kFreeBSD & DragonFly BSD:

    http://hg.savannah.gnu.org/hgweb/mingw-cross-env/rev/dd3d7f4521dc
    http://hg.savannah.gnu.org/hgweb/mingw-cross-env/rev/b314a30667f4

These are "inspired by" the respective package management systems, but
I haven't formulated them as upstream patches. Both systems do some
platform detection and manipulation to determine the "-platform"
argument. I can't imagine doing this easily in our makefiles, and in
both cases the detection amounts to an alias to an underlying "base"
system (linux for Debian, freebsd for DragonFly).

I think it's reasonable to keep these as mingw-cross-env specific
changes for the moment.

Let me know what you think.

Tony