Make sure "make clean" removes everything "make" has created under $(O)

"make clean" would leave behind some files and many directories. Fix
this by correctly tracking the files and directories created under $(O)
during the build process:
- Fix incorrect file names in $(cleanfiles) and add a few missing
ones.
- Introduce a makefile macro: $(cleandirs-for-rmdir), defined in a new
file: mk/cleandirs.mk. It returns the list of directories that should
be removed, given a list of files.
The clean target removes the files, then all the directories in depth-
first order. $(O) is also removed, if found to be empty.

Note that a more straightforward approach was discussed in [1]: use
"rm -rf $(O)/some_dir" and get rid of the whole file and directory
tracking via $(cleanfiles) and $(cleandirs). Although it was agreed it
would be safe, doing so would necessarily break the backward
compatibility for build scripts relying on "make O=<some path>", due to
the additional level ($(O)/some_dir).

Finally, mk/cleandirs.mk is exported to the TA dev kit and the clean
rule for the TAs is updated.

[1] https://github.com/OP-TEE/optee_os/pull/1270

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Andy Green <andy@warmcat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/core/sub.mk b/core/sub.mk
index 4f0375be..0732905d 100644
--- a/core/sub.mk
+++ b/core/sub.mk
@@ -7,3 +7,4 @@ produce-ta_pub_key = ta_pub_key.c
 depends-ta_pub_key = $(TA_SIGN_KEY)
 recipe-ta_pub_key = scripts/pem_to_pub_c.py --prefix ta_pub_key \
 		--key $(TA_SIGN_KEY) --out $(sub-dir-out)/ta_pub_key.c
+cleanfiles += $(sub-dir-out)/ta_pub_key.c