Added some initial support for free toolchains

[KOLANICH]

No description provided.

[SergiusTheBest]

That's interesting! Do you build drivers with mingw? Could you provide some info about your use case?

[KOLANICH]

1 The driver I wanted to build was not buildable with mingw or reaktos ddk.
2 But mingw contain some headers for drivers development and some people have claimed that they used mingw for building drivers.
3 though the headers are incomplete.
4 reactos ddk contains more headers too, though they are also incomplete
5 microsoft wdk is incompatible with gcc
6 microsoft wdk may be compatible with clwng if msvc headers are used
7 some effort is needed to make a frankenstein monster from mingw headers, reactos headers, windows sdk, windows ddk workable without msvc headers. See open-source-ideas/ideas#64 for more info.

[sgeto]

I like the idea.
I would personally put the MinGW/ReactOS stuff in a separate file and call include(), or make them a separate find module altogether

[SergiusTheBest]

@sfhacker Very nice, please keep us posted!

[ddkwork]

Mingw, sys, sure? If the google go language can build sys file,that's best for me.