openpgp: Add support for BZIP2-compressed data packets.
openpgp: Add support for BZIP2-compressed data packets.

Tested using a variety of files encrypted with gpg and the
"--compress-algo BZIP2" gpg option.

R=golang-dev, bradfitz, agl
CC=golang-dev
https://codereview.appspot.com/10801043

Committer: Adam Langley <db68fba232b2c49ed3e9d3081df349dde7b61dfd@golang.org>

tonnerre/golang-go.crypto,drhax9908/go.crypto,xman1101/terminal,isislovecruft/go.crypto,dizzyd/go.crypto,cmars/go.crypto,isislovecruft/go.crypto,polydawn-ports/go.crypto,tonnerre/golang-go.crypto,dizzyd/go.crypto,polydawn-ports/go.crypto,xman1101/terminal,cmars/go.crypto,drhax9908/go.crypto