Vendor dependencies for 0.3.0 release

vendor/crc32fast/build.rs

@@ -0,0 +1,27 @@
+use std::{env, process::Command};
+
+fn main() {
+    if let Some(minor_version) = minor_rustc_version() {
+        // rustc 1.80 stabilized ARM CRC32 intrinsics:
+        // https://doc.rust-lang.org/nightly/core/arch/aarch64/fn.__crc32d.html
+        if minor_version >= 80 {
+            println!("cargo:rustc-cfg=stable_arm_crc32_intrinsics");
+            println!("cargo:rustc-check-cfg=cfg(stable_arm_crc32_intrinsics)");
+        }
+    }
+}
+
+fn minor_rustc_version() -> Option<u32> {
+    Command::new(env::var_os("RUSTC")?)
+        .arg("--version")
+        .output()
+        .ok()
+        .and_then(|output| {
+            std::str::from_utf8(&output.stdout).ok().and_then(|output| {
+                output
+                    .split('.')
+                    .nth(1)
+                    .and_then(|minor_version| minor_version.parse().ok())
+            })
+        })
+}