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
core: main: remove all the spam about including make files

Change-Id: Ifd2ef0e239d16b169c572472416c2c31df62a367
Support building with GNU make 4.0

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

Change-Id: Ifa2ab17454edfcd8b7840a7534f70576286f2864