Bug 1882291. Switch to stdarch_arm_neon_intrinsics feature on rust >=…

…1.78. r=glandium

We only need this on ARM32 because the ARM64 intrinsics are stable.

stdarch_arm_neon_intrinsics was split out from stdsimd here:
rust-lang/stdarch#1486

Differential Revision: https://phabricator.services.mozilla.com/D203039

gfx/qcms/Cargo.toml

@@ -20,3 +20,6 @@ cmyk = []
 
 [dependencies]
 libc = {version = "0.2", optional = true }
+
+[build-dependencies]
+version_check = "0.9"

gfx/qcms/build.rs

@@ -0,0 +1,7 @@
+extern crate version_check as rustc;
+
+fn main() {
+    if rustc::is_min_version("1.78.0").unwrap_or(false) {
+        println!("cargo:rustc-cfg=stdsimd_split");
+    }
+}

gfx/qcms/src/lib.rs

@@ -7,9 +7,11 @@
 #![allow(non_upper_case_globals)]
 // These are needed for the neon SIMD code and can be removed once the MSRV supports the
 // instrinsics we use
-#![cfg_attr(feature = "neon", feature(stdsimd))]
+#![cfg_attr(all(stdsimd_split, target_arch = "arm", feature = "neon"), feature(stdarch_arm_neon_intrinsics))]
+#![cfg_attr(all(stdsimd_split, target_arch = "arm", feature = "neon"), feature(stdarch_arm_feature_detection))]
+#![cfg_attr(all(not(stdsimd_split), target_arch = "arm", feature = "neon"), feature(stdsimd))]
 #![cfg_attr(
-    feature = "neon",
+    all(target_arch = "arm", feature = "neon"),
     feature(arm_target_feature, raw_ref_op)
 
 )]