zlib-rs: adapt neon CPU feature check to avx2 one

if the "neon" target feature is enabled, skip runtime detection. this allows
running and passing the "neon" adler32 tests without requiring the "std"
feature.

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

Author: Fabian-Gruenbichler

zlib-rs/src/cpu_features.rs

@@ -81,8 +81,13 @@ pub fn is_enabled_pclmulqdq() -> bool {
 #[inline(always)]
 pub fn is_enabled_neon() -> bool {
     #[cfg(target_arch = "aarch64")]
-    #[cfg(feature = "std")]
-    return std::arch::is_aarch64_feature_detected!("neon");
+    {
+        #[cfg(target_feature = "neon")]
+        return true;
+
+        #[cfg(feature = "std")]
+        return std::arch::is_aarch64_feature_detected!("neon");
+    }
 
     false
 }