autobench: avoid inreplace

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/autobench.rb

@@ -1,18 +1,17 @@
 require 'formula'
 
 class Autobench < Formula
-  url 'http://www.xenoclast.org/autobench/downloads/autobench-2.1.2.tar.gz'
   homepage 'http://www.xenoclast.org/autobench/'
+  url 'http://www.xenoclast.org/autobench/downloads/autobench-2.1.2.tar.gz'
   md5 'dbd00818840ed8d3c3d35734f0353cff'
 
   depends_on 'httperf'
 
   def install
-    inreplace "Makefile" do |s|
-      s.change_make_var! 'PREFIX', prefix
-      s.change_make_var! 'MANDIR', man1
-    end
-    system "make"
-    system "make install"
+    system "make", "PREFIX=#{prefix}",
+                   "MANDIR=#{man1}",
+                   "CC=#{ENV.cc}",
+                   "CFLAGS=#{ENV.cflags}",
+                   "install"
   end
 end