build-unit-test-docker: Use curl for getting keys

apt-key fails to get keys when behind a firewall. Use curl to
get keys via http proxy and add them using apt-key add.

Tested: docker build and run using "scripts/build-unit-test-docker".

Change-Id: I3fa3e4cdd326681b72a77ac251de76a9359ce706
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
1 file changed