rusticl: Use C-string literals

They got stabilized with Rust 1.77.

Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31510>

src/gallium/frontends/rusticl/mesa/compiler/clc/spirv.rs

@@ -7,6 +7,7 @@ use mesa_rust_gen::*;
 use mesa_rust_util::serialize::*;
 use mesa_rust_util::string::*;
 
+use std::ffi::CStr;
 use std::ffi::CString;
 use std::fmt::Debug;
 use std::os::raw::c_char;
@@ -14,7 +15,7 @@ use std::os::raw::c_void;
 use std::ptr;
 use std::slice;
 
-const INPUT_STR: *const c_char = b"input.cl\0".as_ptr().cast();
+const INPUT_STR: &CStr = c"input.cl";
 
 pub enum SpecConstant {
     None,
@@ -140,7 +141,7 @@ impl SPIRVBin {
             headers: c_headers.as_ptr(),
             num_headers: c_headers.len() as u32,
             source: clc_named_value {
-                name: INPUT_STR,
+                name: INPUT_STR.as_ptr(),
                 value: source.as_ptr(),
             },
             args: c_args.as_ptr(),

src/gallium/frontends/rusticl/mesa/pipe/screen.rs

@@ -357,7 +357,7 @@ impl PipeScreen {
                 });
             if ptr.is_null() {
                 // this string is good enough to pass the CTS
-                CStr::from_bytes_with_nul(b"v0000-01-01-00\0").unwrap()
+                c"v0000-01-01-00"
             } else {
                 CStr::from_ptr(ptr)
             }