nak/sm50: add an annotate debug flag

Add a flag so that users can enable debug annotations when printing the IR.
This does nothing for now. A follow-up commit will actually implement
annotations.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27158>

src/nouveau/compiler/nak/api.rs

@@ -19,6 +19,7 @@ enum DebugFlags {
     Print,
     Serial,
     Spill,
+    Annotate,
 }
 
 pub struct Debug {
@@ -41,6 +42,7 @@ impl Debug {
                 "print" => flags |= 1 << DebugFlags::Print as u8,
                 "serial" => flags |= 1 << DebugFlags::Serial as u8,
                 "spill" => flags |= 1 << DebugFlags::Spill as u8,
+                "annotate" => flags |= 1 << DebugFlags::Annotate as u8,
                 unk => eprintln!("Unknown NAK_DEBUG flag \"{}\"", unk),
             }
         }
@@ -62,6 +64,10 @@ pub trait GetDebugFlags {
     fn spill(&self) -> bool {
         self.debug_flags() & (1 << DebugFlags::Spill as u8) != 0
     }
+
+    fn annotate(&self) -> bool {
+        self.debug_flags() & (1 << DebugFlags::Annotate as u8) != 0
+    }
 }
 
 pub static DEBUG: OnceLock<Debug> = OnceLock::new();