Exclude a few dead_code instances

These are mostly places where a field in a struct is only kept around
for lifetime reasons.

Annotating the individual instances means that we don't have to turn off
the warning for new code.

BUG=b:365852007

Change-Id: I9172ea28cc12779331cd48c2c6ad1003d7ca02f8
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/5966505
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: Dennis Kempin <denniskempin@google.com>

devices/src/register_space/register.rs

@@ -131,6 +131,7 @@ pub trait RegisterInterface: Send {
     /// Handle write.
     fn write(&self, _addr: RegisterOffset, _data: &[u8]) {}
     /// Reset this register to default value.
+    #[allow(dead_code)]
     fn reset(&self) {}
 }
 

src/crosvm/cmdline.rs

@@ -646,6 +646,7 @@ pub struct UsbAttachCommand {
         arg_name = "BUS_ID:ADDR:BUS_NUM:DEV_NUM",
         from_str_fn(parse_bus_id_addr)
     )]
+    #[allow(dead_code)]
     pub addr: (u8, u8, u16, u16),
     #[argh(positional)]
     /// usb device path

swap/tests/common/mod.rs

@@ -18,6 +18,7 @@ pub fn create_uffd_for_test() -> Userfaultfd {
 }
 
 pub struct SharedMemoryMapping {
+    #[allow(dead_code)]
     pub shm: SharedMemory,
     pub mmap: MemoryMapping,
 }