Adds conditional byteswapping intrinsics

These intrinsics are synthesized, so maybe they should be in another
file. But since they are just a single line of code each, based on the
bswap intrinsics and aren't really intended for public consumption (they should be exposed as a
single function / trait) I thought they would fit here.
Implement `map_mut` on the Option type

Closes #7394
configure: Require one of wget or curl.
When an impl references an unknown trait, mention what
the trait is called in the error message.
Add an EnumSetIterator and EnumSet::iter
Move most iter functionality to extra, fixes #7343
extra: docs, tests and new functionality for the extra::stats module
Classify newtype structs S(T) as immediates if T is an immediate
lint: make the non_camel_case_types lint work with scripts without a upper/lowercase distinction.
rustc: add a lint to enforce uppercase statics.
Fix dereference of temporary immediate newtype structs
Improve the attempted dynamic environment-capture error message
Better error messages in report_use_of_moved_value; close #7286
Fix filenames of some compile-fail tests.
Add a run-pass test for recursive copyable stack closures.
Compare values in TreeMap's 'lt' function

Closes #5194
Small documentation changes

I'm leaving the Sized kind undocumented since it isn't fully implemented
yet.
Completely disable rusti on 32-bit hosts
GC static_size_of_enum, which was unused
Fixed documentation for finalize->drop change