Merge remote-tracking branch 'upstream/io' into io

Conflicts:
	src/rt/rustrt.def.in

diff --cc src/rt/rustrt.def.in
index 4d7fa589f6fa76f2b8c5fe5241ab8df4e25e0dee,d85700435e008c41c4e8f5293366dd8b8a28aeda..b604f60cba6e2203d2ef8548291dbb8761d0f7ec
--- 1/src/rt/rustrt.def.in
--- 2/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@@ -247,4 -242,7 +250,7 @@@ rust_valgrind_stack_deregiste
  rust_take_env_lock
  rust_drop_env_lock
  rust_update_log_settings
+ rust_running_on_valgrind
  rust_get_num_cpus
 -rust_current_boxed_region
+ rust_get_global_args_ptr
++rust_current_boxed_region