Reduce code bloat from assert!()

Assertions without a message get a generated message that consists of a
prefix plus the stringified expression that is being asserted. That
prefix is currently a unique string, while a static string would be
sufficient and needs less code.
Revert atomicrmw {max, min, umax, umin}
Implement Zero for unit
Remove unused variables.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
Give tasks useful names. #2891
Move atomically to unstable::sync, and document what it actually does. Close #7872.
auto merge of #8150 : dotdash/rust/assert_bloat, r=huonw

Assertions without a message get a generated message that consists of a
prefix plus the stringified expression that is being asserted. That
prefix is currently a unique string, while a static string would be
sufficient and needs less code.
auto merge of #8151 : sanxiyn/rust/atomicrmw, r=cmr

#8039 broke ARM build, and nothing uses these yet.
std: Remove PortSet. Not supported by new scheduler. Replace uses with SharedChan.
rm ancient error for lowercase kinds

3 of these kinds no longer even exist in the CamelCase form
remove `copy` as a keyword
register snapshots.
auto merge of #8177 : graydon/rust/2013-07-31-register-new-snapshots, r=thestinger

r? someone
make `in` and `foreach` get treated as keywords
convert `pure` to a reserved keyword
auto merge of #8162 : thestinger/rust/no-copy, r=brson
auto merge of #8149 : omasanori/rust/cleanup, r=alexcrichton

Fixed a warning.
rc: from_{owned,const} -> from_{send,freeze}
migrate many `for` loops to `foreach`
auto merge of #8184 : thestinger/rust/retreat, r=huonw