Turn off jemalloc
test: xfail bench/task-perf-one-million. OOM on 32-bit linux w/o opts
replace #[inline(always)] with #[inline]. r=burningtree.
xfail std::num::complex::test_norm on x86, r=burningtree.
rusti: disable tests on 32bit mac. r=burningtree.
std: Work around some failing 'run' tests when valgrinding. #7224

Under valgrind on 64->32 cross compiles the dynamic linker is emitting
some error messages on stderr, which interferes with the tests that
are checking stderr.
rusti: Disable tests on macos harder
std::rt: Work around a dynamic borrowck bug
rustc: Dispose of LLVM passes in test cases
libsyntax: Remove `drop` as a keyword.
Fix update snapshot script for rename
Ignore rustpkg tests
core -> extra for mac
xfail box-related debug-info tests r=snapshot
ignore inherited environment test under valgrind r=snapshot
_Actually_ xfail debuginfo tests
Get cross crate default methods working.

This fixes the large number of problems that prevented cross crate
methods from ever working. It also fixes a couple lingering bugs with
polymorphic default methods and cleans up some of the code paths.

Closes #4102. Closes #4103.