core::iter::order functions now take two types of iterators.

Previously the type signatures of the ordering functions in
`core::iter::order` took two iterators, but only if they were
the same type of iterator.  This commit loosens that restriction
and allows different kinds of iterators (but with the same type
of elements) to be compared.
Reset the terminal color before the newline for diagnostics

When printing colored diagnostics, we need to reset the terminal before
emitting the newline, not after. Otherwise it gets line-buffered and the
color won't reset until the next line is printed or the compiler exits.

Normally this isn't a problem, but when running rustc in parallel with
other processes (e.g. `make -j4`) this can cause the color to leak
to other lines.
auto merge of #14289 : TyOverby/rust/master, r=alexcrichton

Closes #14278.

Previously the type signatures of the ordering functions in `core::iter::order` took two iterators, but only if they were the same type of iterator.  This commit loosens that restriction and allows different kinds of iterators (but with the same type of elements) to be compared.
auto merge of #14296 : kballard/rust/diagnostic_color_newline, r=alexcrichton

When printing colored diagnostics, we need to reset the terminal before
emitting the newline, not after. Otherwise it gets line-buffered and the
color won't reset until the next line is printed or the compiler exits.

Normally this isn't a problem, but when running rustc in parallel with
other processes (e.g. `make -j4`) this can cause the color to leak
to other lines.
Correct EBNF grammar in the manual

The grammar for use declarations was outdated.
auto merge of #14277 : pczarn/rust/manual-grammar, r=alexcrichton

The grammar for use declarations was outdated. Corrected some other mistakes.
compiletest: Refactor compile-fail to regex.
auto merge of #14283 : Ryman/rust/commented_compile_fail_error, r=kballard

Edit: This now only covers refactoring to regex.