Distinguish between enabling the library and enabling shared libraries

Some tests for capsule-capture-libs will need to compile shared
libraries, even if libcapsule itself is not built.

Signed-off-by: Simon McVittie <smcv@collabora.com>
3 jobs for master in 15 minutes and 42 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #15990
build:bionic

00:15:41

passed #15989
build:buster

00:15:06

passed #15988
build:stretch

00:15:40