Add basic definitions for MCST LCC and their Elbrus architecture

[a1batross]

It successfully builds vcpkg binary. I've tried building zlib after providing e2k-linux triplet and it works.

Elbrus technically has much more ABIs, specifying the architecture level or through backwards incompatible CPU target and ILP32 and so-called protected mode with large pointers that carry the size of allocation and an offset. Nothing of this I intend to support.

[a1batross]

@microsoft-github-policy-service agree

[BillyONeal]

How did you end to end test that this works? I understand that we don't have the hardware but we would at least like to see evidence like a screenshot or something like that it works

[a1batross]

How did you end to end test that this works? I understand that we don't have the hardware but we would at least like to see evidence like a screenshot or something like that it works

@BillyONeal thanks, yeah, you're right. I initially set it up for one project that used vcpkg, but it turned out it also supports fetching system-wide dependencies through pkg-config, so I ended up not using vcpkg for it.

However, I would like to do more tests with real projects and will post the results here. The selection might be somewhat limited, as not all software compiles with LCC, targetting Elbrus, out of the box. Also cross compilation is also in my plans.

[BillyONeal]

@a1batross We don't need to see that it did exactly what you needed in order to land this, but we do need to see that it succeeded at something, if that makes sense.

The point is that we don't want to add knobs for this or similar only for the first time some tries it to explode because we are missing a toolchain, triplet file, etc. This change on its own seems unlikely to actually function.