Fixed -Z print-link-args
std::str: Bench test for char iterators
std::str: Small fix for slice
std::str: Special case char_range_at_reverse so it is faster

Implement char_range_at_reverse similarly to char_range_at, instead of
re-using that method.
std::str: Add str::raw::slice_unchecked

Add a function like raw::slice_bytes, but it doesn't check slice
boundaries. For iterator use where we always know the begin, end indices
are in range.
std::str: Implement CharIterator separately

Let CharIterator be a separate type from CharOffsetIterator (so that
CharIterator can be cloned, for example).

Implement CharOffsetIterator by using the same technique as the method
subslice_offset.
std::str: Use CharOffsetIterator in .find() and .rfind()
std::str: Correct docstrings for lack of null terminator in ~str and &str
std::str: Only check char boundary for end index in .slice_to()
std::str: Use CharOffsetIterator in slice_chars
std::str: Improve comments for CharIterator
Fix some parsing errors in extra::url

Fixes issue #8612.
std::str: Use iterators instead of while loops for CharSplitIterator

Embed an iterator in the CharSplitIterator struct, and combine that with
the former bool `only_ascii`; so use an enum instead.
Rename functional-struct-update.rs to avoid tripping Windows installer detector.
(The "update" keyword in the test name makes Windows want to run it with elevated privileges, which fails of course)
Prevent Send, Freeze, and Sized from being manually implemented. Close #8517.
Allow traits to use builtin kinds as supertraits for #7083.
Add tests for #7083.
Add more capabilities to typarams bounded by traits with super-builtin-kinds. Close #7083.
Add tests for super-builtin-kind capabilities (#7083)
Fixup style of test cases for #7083