build: Add SKIP_SET_METADATA flag

On some of the older devices the recovery doesn't support
metadata when setting permissions. This allows to use
set_perm vs set_metadata.
Enable this behavior by setting SKIP_SET_METADATA := true

Change-Id: Ib6cf97b5ca28cee8a87975231f3a61b156e77d29
core: main: remove all the spam about including make files

Change-Id: Ifd2ef0e239d16b169c572472416c2c31df62a367
envsetup: do not print an error if complete fails

complete is a bashism; so it will fail on other shells. Avoid printing
an error if that is the case.

Change-Id: Id6d6311792f409cc3a697c7a2bb003863f1afe60
envsetup: drop unnecesary exports

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

Change-Id: I9228cef0c4a9543b3d34fdc39a368ad0238431e2
envsetup: Mark zsh as compatible

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

Change-Id: I02e5e3bedf56b43104c280d9737ae7b334357643
Support building with GNU make 4.0

* It works just fine, no need for the warning.

Change-Id: Ifa2ab17454edfcd8b7840a7534f70576286f2864
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0