Makefile: Do not mark file targets as .PHONY target

Only non-file targets should be set a .PHONY. Otherwise if file target is
set as .PHONY then targets which depends on those file .PHONY targets would
be always rebuilt even when their prerequisites are not changed.

File target which needs to be always rebuilt can be specified in Make
system via having a prerequisite on some .PHONY target, instead of marking
whole target as .PHONY. In Makefile projects it is common to create empty
.PHONY target named FORCE for this purpose.

This patch changes all file targets which are set as .PHONY to depends on
new .PHONY target FORCE, to ensure that these file targets are always
rebuilt (as before). Basically they are those targets which calls external
make subprocess.

After FORCE target is specified in main Makefile, remove it from other
Makefile files to prevent duplicate definitions.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: Iee3b4e0de93879b95eb29a1745a041538412e69e
5 files changed