In each subdir that is a target for symlinks, automatically ignore the results
of gen_links():
- At the top of gen_links.sh.inc, clear the .gitignore.
- In the loop, add each link name to the local .gitignore.
- In selected gen_links.sh, there is also a "manual" link creationg. So that
this also ends up in the local .gitignore, have the link creation as separate
gen_link() macro which at the same time adds to ./.gitignore.
- in the root .gitignore, ignore all the subdirs' generated */.gitignore files.
Change-Id: I73c11fe8362358bf7e1bdf0e1be53399b5d3351b