Mostly picking the same paths as FreeBSD.
We need a little special handling for crt files, as netbsd uses its
own (and not GCC's) for those, with slightly different names.
* zig fmt
* std.mem.join takes a slice of slices instead of var args
* std.mem.join takes a separator slice rather than byte,
and always inserts it. Previously it would not insert the separator
if there already was one, violating the documented behavior.
* std.mem.join calculates exactly the correct amount to allocate
and has no call to allocator.shrink()
* bring back joinWindows and joinPosix and the corresponding tests.
it is intended to be able to call these functions from any OS.
* rename std.os.path.resolveSlice to resolve (now resolve takes
a slice of slices instead of var args)
* rename std.mem.split to std.mem.tokenize
* add future deprecation notice to docs
* (unrelated) add note to std.os.path.resolve docs
* std.mem.separate - assert delimiter.len not zero
* fix implementation of std.mem.separate to respect the delimiter
* separate the two iterators to different structs
* error.BadFd is not a valid error code. it would always be a bug to
get this error code.
* merge error.Io with existing error.InputOutput
* merge error.PathNotFound with existing error.FileNotFound.
Not all OS's support both.
* add os.File.openReadC
* add error.BadPathName for windows file operations with invalid
characters
* add os.toPosixPath to help stack allocate a null terminating byte
* add some TODOs for other functions to investigate removing the
allocator requirement
* optimize some implementations to use the alternate functions when
a null byte is already available
* add a missing error.SkipZigTest
* os.selfExePath uses a non-allocating API
* os.selfExeDirPath uses a non-allocating API
* os.path.real uses a non-allocating API
* add os.path.realAlloc and os.path.realC
* convert many windows syscalls to use the W versions (See #534)
