Support armv7-unknown-linux-gnueabi and armv7-unknown-linux-musleabi (soft-float variants)

[adrian-budau]

Currently for armv7 only the hardfloat variants (armv7-unknown-linux-gnueabihf and armv7-unknown-linux-musleabihf) are supported.

I'll try to open a pull request as this seems to be a small change.

[hellow554]

Is there a reason you don't use the thumbv7*-* targets instead?

[adrian-budau]

None of those targets support the std. In particular I require only the armv7-unknown-linux-muselabi target, but I mentioned both because it makes sense.

And arm-unknown-linux-musleabi doesn't work because some instructions use the CP15 register which is disabled/does not exist on our hardware (it's not particularly clear for us).