Makefile.include: Add line continuations between $(eval) calls

Older GNU Make versions (e.g. v4.1) don't like the `mark_missing_deps`
macro without line continuations. Probably because the lines are tech-
nically empty after evaluation.

Change-Id: I790c21999b2fc9c698f6bf9302f670470fe1bab8
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/73749
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
1 file changed