+ * libprotobuf-c, protoc-c (optional)
+ Used by the `pinba' plugin to generate a parser for the network packets
+ sent by the Pinba PHP extension.
+ <http://code.google.com/p/protobuf-c/>
+
+ * libpython (optional)
+ Used by the `python' plugin. Currently, only 2.3 ≦ Python < 3 is supported.
+ <http://www.python.org/>
+