go: host platform must always be the last one built

Each cross-compiler step also rebuilds the host platform.  If
ENABLE_CGO=0 in a later build step, important OS routines (like looking
up x509 certificates in the keychain) are not implemented even for the
host platform.

Closes #17758.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
asymptote: reformat caveats
formula: cinch up formatting
when 1.1.30

Closes #17753.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
qemu: add sdl option.

Closes #17754.
redis 2.6.10

Closes #17764.
lbzip2: 2.2 (new formula).

A parallel bzip2 compatible (un)archiver.

Closes #17767.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
lbzip2: add test.
rbenv: use HOMEBREW_PREFIX.

Closes #17778.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
heroku-toolbelt: add heroku alias.

Closes #17784.
update gnutls to 3.1.8 to fix a major bug
http://article.gmane.org/gmane.comp.encryption.gpg.gnutls.devel/6623