libatomic_ops: 7.2d - portable atomic operations

Add a new formula for libatomic_ops that provides portable atomic
operations on many platforms.

Closes Homebrew/homebrew#21757.

Signed-off-by: Xiyue Deng <manphiz@gmail.com>

Formula/libatomic_ops.rb

@@ -0,0 +1,14 @@
+require 'formula'
+
+class LibatomicOps < Formula
+  homepage 'http://www.hpl.hp.com/research/linux/atomic_ops/'
+  url 'http://www.hpl.hp.com/research/linux/atomic_ops/download/libatomic_ops-7.2d.tar.gz'
+  sha1 'ed5bb963648bdfb87fc815a9037114654d164907'
+
+  def install
+    system "./configure", "--disable-dependency-tracking", "--prefix=#{prefix}"
+    system "make"
+    system "make", "check"
+    system "make", "install"
+  end
+end