ganglia: use checksummed patches

Formula/ganglia.rb

@@ -12,11 +12,10 @@ class Ganglia < Formula
   depends_on 'pcre'
   depends_on 'rrdtool'
 
-  def patches
-    # fixes build on Leopard and newer, which lack kvm.h and its corresponding /dev/ node
-    {:p0 => [
-      "https://trac.macports.org/export/105820/trunk/dports/net/ganglia/files/patch-libmetrics-darwin-metrics.c.diff"
-    ]}
+  # fixes build on Leopard and newer, which lack kvm.h and its corresponding /dev/ node
+  patch :p0 do
+    url "https://trac.macports.org/export/105820/trunk/dports/net/ganglia/files/patch-libmetrics-darwin-metrics.c.diff"
+    sha1 "71a864d46ac963fec3709cd5eea61856b1eb0c93"
   end
 
   def install