colletd: add debug option

Closes Homebrew/homebrew#20578.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/collectd.rb

@@ -7,6 +7,7 @@ class Collectd < Formula
 
   # Will fail against Java 1.7
   option "java", "Enable Java 1.6 support"
+  option "debug", "Enable debug support"
 
   depends_on 'pkg-config' => :build
   depends_on :python
@@ -31,6 +32,7 @@ class Collectd < Formula
 
     args << "--disable-embedded-perl" if MacOS.version == :leopard
     args << "--disable-java" unless build.include? "java"
+    args << "--enable-debug" if build.include? "debug"
 
     system "./configure", *args
     system "make install"