feat(ci): build SPM in the build directory

Similar to tfa and tftf, having a separate build directory whenever
building is useful to allow parallel builds. Otherwise every
simultaneous build will have its artefacts conflict with the others,
causing all to fail in a variety of ways.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I6b923e06c2b3398e3eb4866e87a45d2c23530c10
1 file changed