New formula google-sparsehash

An extremely memory-efficient hash_map implementation. 2 bits/entry overhead!
The SparseHash library contains several hash-map implementations, including
implementations that optimize for space or speed.

These hashtable implementations are similar in API to SGI's hash_map class and
the tr1 unordered_map class, but with different performance characteristics.
It's easy to replace hash_map or unordered_map by sparse_hash_map or
dense_hash_map in C++ code.

Formula/google-sparsehash.rb

@@ -0,0 +1,13 @@
+require 'formula'
+
+class GoogleSparsehash <Formula
+  url 'http://google-sparsehash.googlecode.com/files/sparsehash-1.7.tar.gz'
+  homepage 'http://code.google.com/p/google-sparsehash/'
+  sha1 'b9355e6aa2564b6a2d9fc2e1ac3f9773dbca8f59'
+
+  def install
+    system "./configure", "--disable-debug", "--disable-dependency-tracking", "--prefix=#{prefix}"
+    system "make check"
+    system "make install"
+  end
+end