Forbid whitespace before colon in sudoers tags

[0x2b3bfa0]

Closes #153, but is a breaking change. Not sure if the issues this pull request can cause would outweigh the benefits.

Warning
This pull request modifies the parser and updates a generated file. It goes whithout saying that this generated file should be verified as part of the code review process, by running make and verifying that the toke.c files are identical. Reproducible with Flex 2.6.4, from Ubuntu 20.04 repositories.

sudo/INSTALL.md

Lines 18 to 23 in e4ea5ad

	If you wish to modify the parser then you will need flex version
	2.5.2 or later and either bison or byacc (sudo comes with a
	pre-generated parser). You'll also have to run configure with the
	--with-devel option or pass DEVEL=1 to make. You can get flex from
	https://github.com/westes/flex/. You can get GNU bison from
	https://ftp.gnu.org/pub/gnu/bison/ or any GNU mirror.

[millert]

In general I try to avoid breaking existing sudoers files. I believe the right thing is to treat this as a doc bug and update the manual so that it is clear that whitespace is allowed before the colon.