Remove auto_regeneration=0 frm envsetup_functions.sh.

It only has an effect with the make generator, which is no longer used.

BUG=330631

Review URL: https://codereview.chromium.org/104973003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242547 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242547