Build - envsetup: drop unnecesary exports

export -f is a bashism and we don't actually need it, so lets remove it.

Change-Id: I029763cdb0d0787368d7bd7619da23815976921e
Signed-off-by: STELIX <ssspinni@gmail.com>
Build - envsetup: Mark zsh as compatible

Basic functionality has been tested on zsh 5.0.2 and has been found to
work correctly.

Change-Id: I823964e41d38c857aacdde4b4530b879a4367e38
Signed-off-by: STELIX <ssspinni@gmail.com>