Add some more #[inline] annotations for trivial functions (#2817)

Looking at some profiles these or their related functions were all
showing up, so this commit adds `#[inline]` to allow cross-crate
inlining by default.

cranelift/entity/src/lib.rs

@@ -70,21 +70,25 @@ macro_rules! entity_impl {
     // Basic traits.
     ($entity:ident) => {
         impl $crate::EntityRef for $entity {
+            #[inline]
             fn new(index: usize) -> Self {
                 debug_assert!(index < ($crate::__core::u32::MAX as usize));
                 $entity(index as u32)
             }
 
+            #[inline]
             fn index(self) -> usize {
                 self.0 as usize
             }
         }
 
         impl $crate::packed_option::ReservedValue for $entity {
+            #[inline]
             fn reserved_value() -> $entity {
                 $entity($crate::__core::u32::MAX)
             }
 
+            #[inline]
             fn is_reserved_value(&self) -> bool {
                 self.0 == $crate::__core::u32::MAX
             }
@@ -93,6 +97,7 @@ macro_rules! entity_impl {
         impl $entity {
             /// Create a new instance from a `u32`.
             #[allow(dead_code)]
+            #[inline]
             pub fn from_u32(x: u32) -> Self {
                 debug_assert!(x < $crate::__core::u32::MAX);
                 $entity(x)
@@ -100,6 +105,7 @@ macro_rules! entity_impl {
 
             /// Return the underlying index value as a `u32`.
             #[allow(dead_code)]
+            #[inline]
             pub fn as_u32(self) -> u32 {
                 self.0
             }