Makefile: Create distdir before using it

If distdir doesn't already exist in the chameleon directory, writing the
commit file to it will fail.

        bash: ./dist/commit: No such file or directory

BUG=None
TEST=make clean && make

Change-Id: I1e474d157b697b51ce4b89bc044690985aab3fe3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/2194377
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>
Commit-Queue: Shyh-In Hwang <josephsih@chromium.org>
Tested-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Auto-Submit: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
1 file changed