misc/dist: require 10.6 or later for OS X .pkgs
This changes the misc/dist program to generate OS X
packages using pkgbuild and productbuild.
The productbuild utility makes it easy to generate
packages with a custom Distribution file. This allows
us to add an installcheck script that presents a
friendly message to users who are running on an old
version of Mac OS X.
The change also fixes a few issues with the
postinstall script:
- In-repo version of the script has been made
executable. Installers generated using the new
tools couldn't execute it otherwise.
- It now uses -d for checking for the existence
of the Xcode specs directory.
- The call to sudo.bash has been dropped since cov
and prof aren't bundled with the binary
distributions.
Fixes #3455.
Tested on 10.5.8, 10.6.0, 10.6.8 and 10.7.3.
R=adg, golang-dev
CC=golang-dev
https://golang.org/cl/
5987044