* std.c: consolidate some definitions, making them share code. For
example, freebsd, dragonfly, and openbsd can all share the same
`pthread_mutex_t` definition.
* add type safety to std.c.O
- this caught a bug where mode flags were incorrectly passed as the
open flags.
* 3 fewer uses of usingnamespace keyword
* as per convention, remove purposeless field prefixes from struct field
names even if they have those prefixes in the corresponding C code.
* fix incorrect wasi libc Stat definition
* remove C definitions from incorrectly being in std.os.wasi
* make std.os.wasi definitions type safe
* go through wasi native APIs even when linking libc because the libc
APIs are problematic and wasteful
* don't expose WASI definitions in std.posix
* remove std.os.wasi.rights_t.ALL: this is a footgun. should it be all
future rights too? or only all current rights known? both are
the wrong answer.
std.fs.dir.makePath silently failed if one of the items in the path already exists. For example:
cwd.makePath("foo/bar/baz")
Silently failing is OK if "bar" is already a directory - this is the intended use of makePath (like mkdir -p). But if bar is a file then the subdirectory baz cannot be created - the end result is that makePath doesn't do anything which should be a detectable error because baz is never created.
The existing code had a TODO comment that did not specifically cover this error, but the solution for this silent failure also accomplishes the TODO task - the code now stats "foo" and returns an appropriate error. The new code also handles potential race condition if "bar" is deleted/permissions changed/etc in between the initial makeDir and statFile calls.
