[OE-core] help2man

[Richard Purdie]

The more I look at and think about help2man, the more it looks like
something we just shouldn't need/use.

In summary, it runs a binary and captures its --help output. This rules
it out from being useful in most cross compiling scenarios, i.e. all
target packages.

In the -native/-cross cases, we don't really care about man pages.

I'm therefore thinking we should really just drop the dependency and
symlink help2man to /bin/false. The missing script in autotools should
then just silently touch the man page files instead of regenerating
them.

I tried to figure out which recipes actually use help2man:

$ grep HELP2MAN * -r --exclude=Makefile.in 2> /dev/null | grep -v missing

and against a core-image-sato this gave:

libtool
libtasn1
gettext
automake
autoconf
flex
bison
m4

which isn't that many recipes to go and beat up manually if necessary.
It certainly doesn't warrant a global include in autotools.bbclass IMO.

Cheers,

Richard