zerotier: do not allow executable stack

zerotier: do not allow executable stack

zerotier as default has executable stack.
[   11.343143] process '/usr/bin/zerotier-one' started with executable stack

executable stacks are not recommend, possibly provide a threat and there
seems to be no advantage of executable stack with zerotier-one - so let's
build it without instead.

Stack is executable on x86_64, but not on all archs, such as ramips.

Signed-off-by: Oskari Rauta <oskari.rauta@gmail.com>
(cherry picked from commit 56f30520f2413f9f1434def5b533a265912aea1c)