std: add platform support for hexagon-unknown-qurt

[androm3da]

QuRT provides POSIX-like APIs for basic operations, so this implementation reuses the unix platform abstraction layer with QuRT-specific customizations.

Platform modules:

• New os::qurt module with platform-specific extensions to ffi, fs, io, raw
• QuRT-specific file handling for ino, dev, mode, nlink, etc.

Unsupported: Networking, fork/exec, pipe, chown/fchown/lchown/chroot/mkfifo

[rustbot]

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[androm3da]

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] object test:false 8.081
error[E0308]: mismatched types
    --> library/std/src/sys/process/unix/unix.rs:408:56
     |
 408 |         libc::execvp(self.get_program_cstr().as_ptr(), self.get_argv().as_ptr() as *const *mut _);
     |         ------------                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ types differ in mutability
     |         |
     |         arguments to this function are incorrect
     |
     = note: expected raw pointer `*const *const u8`
                found raw pointer `*const *mut _`
note: function defined here
    --> /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.178/src/unix/mod.rs:1046:12
     |
1046 |     pub fn execvp(c: *const c_char, argv: *const *const c_char) -> c_int;
     |            ^^^^^^

For more information about this error, try `rustc --explain E0308`.
[RUSTC-TIMING] std test:false 6.188
error: could not compile `std` (lib) due to 1 previous error

[joboet]

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

You need libc at 0.2.179, right? You can update libc here – but please keep it in a separate commit.

[joboet]

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[androm3da]

This PR depends on a newer version of the libc crate - maybe I'll let this PR hang here for a bit and check back in when it gets released and promoted?

You need libc at 0.2.179, right? You can update libc here – but please keep it in a separate commit.

The commit I need - rust-lang/libc@9934c04 is not yet tagged/released. Or rather there is a ctest-* tag but I suspect that doesn't apply/not intended use for that tag. Should I try to execute a tag/release of libc, or just wait for that to happen naturally?

[rust-bors]

☔ The latest upstream changes (presumably #152373) made this pull request unmergeable. Please resolve the merge conflicts.