mk: target triple rename arm-unknown-android->arm-linux-androideabi
auto merge of #5436 : alexcrichton/rust/assert-message, r=pcwalton

This would close #2761. I figured that if you're supplying your own custom message, you probably don't mind the stringification of the condition to not be in the message.
auto merge of #5350 : yichoi/rust/pull-0313-2, r=graydon,pcwalton

FIX #5330

rename arm-unknown-android to arm-linux-androideabi
rustc: Removing lots of bad copies in match clauses
syntax: remove bad copies in match