mk: arm support - disable tls of jemalloc on rt.mk
std: remove the invalid NullTerminatedStr instance for &'static str.

A slice of a 'static str is still 'static, but doesn't necessarily
have the null terminator.
auto merge of #7094 : yichoi/rust/arm_jemalloc, r=thestinger

rt.mk : 
  in case of arm, add --disable-tls at jemalloc configure
  (to solve SEGV)
auto merge of #7096 : huonw/rust/invalid-null-str, r=thestinger

A slice of a 'static str is still 'static, but doesn't necessarily
have the null terminator.
Add some 0.7 release notes
hashmap: remove leftover debug!() logging
auto merge of #7099 : brson/rust/releasenotes, r=thestinger
auto merge of #7100 : thestinger/rust/hashmap, r=pnkfelix

Not much point in leaving these around. They just get in the way when you actually want to log something else.
Remove unused imports

I was able to remove unused imports, and fix the following warnings

src/libstd/hashmap.rs:23:15: 23:23 warning: unused import [-W unused-imports (default)]
src/libstd/task/spawn.rs:95:15: 95:23 warning: unused import [-W unused-imports (default)]
src/libstd/rt/uv/mod.rs:42:0: 42:9 warning: unused import [-W unused-imports (default)]
src/libstd/rt/uv/mod.rs:45:0: 45:9 warning: unused import [-W unused-imports (default)]
src/librustc/middle/trans/meth.rs:26:0: 26:26 warning: unused import [-W unused-imports (default)]
src/librustc/back/link.rs:210:20: 210:25 warning: unused import [-W unused-imports (default)]

I was unable to fix the following unused import warnings. The code
here was weird.

src/libextra/std.rc:40:11: 40:14 warning: unused import [-W unused-imports (default)]
src/libextra/std.rc:40:16: 40:24 warning: unused import [-W unused-imports (default)]
auto merge of #7105 : sstewartgallus/rust/removed_unused_imports, r=sanxiyn

I was able to remove unused imports, and fix the following warnings

src/libstd/hashmap.rs:23:15: 23:23 warning: unused import [-W unused-imports (default)]
src/libstd/task/spawn.rs:95:15: 95:23 warning: unused import [-W unused-imports (default)]
src/libstd/rt/uv/mod.rs:42:0: 42:9 warning: unused import [-W unused-imports (default)]
src/libstd/rt/uv/mod.rs:45:0: 45:9 warning: unused import [-W unused-imports (default)]
src/librustc/middle/trans/meth.rs:26:0: 26:26 warning: unused import [-W unused-imports (default)]
src/librustc/back/link.rs:210:20: 210:25 warning: unused import [-W unused-imports (default)]

I was unable to fix the following unused import warnings. The code
here was weird.

src/libextra/std.rc:40:11: 40:14 warning: unused import [-W unused-imports (default)]
src/libextra/std.rc:40:16: 40:24 warning: unused import [-W unused-imports (default)]
Rename all files with the 'rc' extension
Deny common lints by default for lib{std,extra}
Allow common warnings in stage0 because there may be bugs