rusticl: replace unnecessary Vec references with slice refs

v2: restore static borrow on `core::device::devs()`

Reviewed-by: @LingMan
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34389>

src/gallium/frontends/rusticl/core/device.rs

@@ -1180,7 +1180,7 @@ impl Device {
     }
 }
 
-pub fn devs() -> &'static Vec<Device> {
+pub fn devs() -> &'static [Device] {
     &Platform::get().devs
 }
 

src/gallium/frontends/rusticl/core/program.rs

@@ -560,7 +560,7 @@ impl Program {
 
         let mut res = true;
         for dev in devs {
-            if !self.do_compile(dev, options, &Vec::new(), &mut info) {
+            if !self.do_compile(dev, options, &[], &mut info) {
                 res = false;
                 continue;
             }