Some improvements to the Cargo compiler file.
Use rustc's errorformat and add option to specify permanent parameters.
Updates based on kballard's feedback.
Added check for absolute file path, removed hard tab, and added documentation for new option.
Fix `Vec::map_in_place` not doing what is written in the comment
Fix for issue #17574
Look for standard crates in LIBDIR provided by --libdir option,
not in hardcoded libdir path. If there was no LIBDIR provided
during configuration fallback to hardcoded paths.

Thanks to Jan Niklas Hasse for solution and to Alex Crichton for improvements.

Closes #11671
Conformed the 100 char limit and changed colon to semicolon
Adding switch in vim plugin to toggle format opts
Add myself as an author
Rename json::List to json::Array

Fixes #19010
Fix some English spelling errors
mk/cfg: add .mk suffix on files to avoid "supprises" when backup files (file~) are in the directory
removed usage of struct_variant feature as it is no longer gated
removed struct_variant feature from tests
Update the Vim syntax prelude.
fixed markdown rendering a H1 in comment
test/run-make: some test cases lacked $(EXTRACFLAGS).

Signed-off-by: NODA, Kai <nodakai@gmail.com>
Removed unneeded conversion to a slice.

Vec<T> can index now so its a useless conversion.
doc: adding example for type definitions