Remove more #[must_use] from portable-simd

    warning: `#[must_use]` attribute cannot be used on trait methods in impl blocks
       --> crates/core_simd/src/masks/bitmask.rs:173:5
        |
    173 |     #[must_use = "method returns a new mask and does not mutate the original value"]
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |
        = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
        = help: `#[must_use]` can be applied to data types, foreign functions, functions, inherent methods, provided trait methods, required trait methods, traits, and unions
        = note: `#[warn(unused_attributes)]` (part of `#[warn(unused)]`) on by default

    warning: `#[must_use]` attribute cannot be used on trait methods in impl blocks
       --> crates/core_simd/src/masks/bitmask.rs:190:5
        |
    190 |     #[must_use = "method returns a new mask and does not mutate the original value"]
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |
        = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
        = help: `#[must_use]` can be applied to data types, foreign functions, functions, inherent methods, provided trait methods, required trait methods, traits, and unions

    warning: `#[must_use]` attribute cannot be used on trait methods in impl blocks
       --> crates/core_simd/src/masks/bitmask.rs:206:5
        |
    206 |     #[must_use = "method returns a new mask and does not mutate the original value"]
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |
        = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
        = help: `#[must_use]` can be applied to data types, foreign functions, functions, inherent methods, provided trait methods, required trait methods, traits, and unions

    warning: `#[must_use]` attribute cannot be used on trait methods in impl blocks
       --> crates/core_simd/src/masks/bitmask.rs:222:5
        |
    222 |     #[must_use = "method returns a new mask and does not mutate the original value"]
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |
        = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
        = help: `#[must_use]` can be applied to data types, foreign functions, functions, inherent methods, provided trait methods, required trait methods, traits, and unions

Author: dtolnay

library/portable-simd/crates/core_simd/src/masks/bitmask.rs

@@ -170,7 +170,6 @@ where
 {
     type Output = Self;
     #[inline]
-    #[must_use = "method returns a new mask and does not mutate the original value"]
     fn bitand(mut self, rhs: Self) -> Self {
         for (l, r) in self.0.as_mut().iter_mut().zip(rhs.0.as_ref().iter()) {
             *l &= r;
@@ -187,7 +186,6 @@ where
 {
     type Output = Self;
     #[inline]
-    #[must_use = "method returns a new mask and does not mutate the original value"]
     fn bitor(mut self, rhs: Self) -> Self {
         for (l, r) in self.0.as_mut().iter_mut().zip(rhs.0.as_ref().iter()) {
             *l |= r;
@@ -203,7 +201,6 @@ where
 {
     type Output = Self;
     #[inline]
-    #[must_use = "method returns a new mask and does not mutate the original value"]
     fn bitxor(mut self, rhs: Self) -> Self::Output {
         for (l, r) in self.0.as_mut().iter_mut().zip(rhs.0.as_ref().iter()) {
             *l ^= r;
@@ -219,7 +216,6 @@ where
 {
     type Output = Self;
     #[inline]
-    #[must_use = "method returns a new mask and does not mutate the original value"]
     fn not(mut self) -> Self::Output {
         for x in self.0.as_mut() {
             *x = !*x;