illumos gate

After https://www.illumos.org/issues/7384, all existing illumos Makefiles can be automatically revised using infer_make_gitignore.pl:

$ find usr/ -name Makefile\* | xargs ./usr/src/tools/scripts/infer_make_gitignore.pl

Testing for https://www.illumos.org/issues/7384 already shows that object files and final targets are identical. With this case, after a full illumos-gate build, git-status shows "working directory clean".

Further testing shows that:
1) after a full illumos-gate build, there will have been created many usr/src/**/.gitignore files such that git-status still shows "working directory clean";

2) no descendant .gitignore file excludes files that would normally have been committed. This is confirmed by this sequence of actions:

a) git-archive illumos-gate to a .tar.gz;
b) explode the .tar.gz to a new directory, illumos-gate-files (that will not have a .git directory yet);
c) copy all the descendant .gitignores created in the illumos-gate full build via: find usr/ -name .gitignore -print -exec cp "{}" ../illumos-gate-files/"{}" \; #;
d) git-init, git-add, and git-commit in illumos-gate-files;
e) remove all descendant .gitignore files in illumos-gate-files via: find usr/ -name .gitignore | xargs rm #;
f) git-status still shows "working directory clean";