Add armv7 assembly for cc-test

[glandium]

No description provided.

[alexcrichton]

Thanks! Is there any particular reason for adding this though?

[glandium]

I independently rediscovered #627 (since it's not in a release), and was trying to get a simple STR using cc-test to open an issue, but it was not building at all because of the lack of armv7.S.

[alexcrichton]

Ah ok makes sense! FWIW I think the _asm symbol can be removed since that's just me being too lazy to use preprocessor differences to deal with macos/linux differences in the x86_64.S file.