bitbake.conf: Drop oldincludedir

bitbake.conf: Drop oldincludedir

Autoconf defines this as:

"The directory for installing C header files for non-GCC compilers."

Whilst this is something autoconf does allow changing, I find it hard
to believe it has much use in the wild now and that headers don't get
split like this in reality, it would probably only be useful on really
old unixes.. The values are the same in our configuration anyway.

Drop the value and just use includedir everywhere.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>