Time elapsed for a single board build with ccache typically measures well below 10 seconds. Improve the measurements to milliseconds resolution using bash EPOCHREALTIME (pseudo) environment variable. Change-Id: Iaedc470bb45cf9bb6f14ff8b37cd6f7ae3818a08 Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/75802 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>