Add Archlinux AUR package.

ci/sha256.sh

@@ -1,15 +1,25 @@
 #!/bin/sh
 
+set -e
+
 if [ $# != 1 ]; then
   echo "Usage: $(basename $0) version" >&2
   exit 1
 fi
 version="$1"
 
+# Linux and Darwin builds.
 for arch in i686 x86_64; do
   for target in apple-darwin unknown-linux-musl; do
     url="https://github.com/BurntSushi/ripgrep/releases/download/$version/ripgrep-$version-$arch-$target.tar.gz"
-    sha=$(curl -L -s "$url" | sha256sum)
-    echo $version-$arch-$target $sha
+    sha=$(curl -sfSL "$url" | sha256sum)
+    echo "$version-$arch-$target $sha"
   done
 done
+
+# Source.
+for ext in zip tar.gz; do
+  url="https://github.com/BurntSushi/ripgrep/archive/$version.$ext"
+  sha=$(curl -sfSL "$url" | sha256sum)
+  echo "source.$ext $sha"
+done