Add support for musl-libc on Linux

[Lei Zhang via cfe-commits]

Hi,

I'm replying to this thread; sorry I wasn't subscribed to the list,
thus cannot reply to it directly.

http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20160606/161733.html

Joerg, thanks for your reply. Could you please tell me what kind of
test cases I should prepare?


Thanks,
Lei