share: Delete bitrotted make_*_driver.sh scripts

These scripts have not seen the necessary changes to keep them up to
date with current KPIs and coding practices. They use I/O ports directly
rather than any bus abstractions, use i386 (which is on the way out for
kernel configs) as the architecture of choice for generated kernel
configs, use ISA KPIs, use INTR_TYPE_FAST (renamed in 2000 to INTR_FAST
and removed in 2011), and likely have other issues too that render them
more harm than good for the uninitiated developer looking for a driver
template. If anyone wants to invest time in modernising them they can do
so and bring them back, but for now delete them.

Reviewed by:	cperciva, imp, emaste
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D50468

tools/build/mk/OptionalObsoleteFiles.inc

@@ -1683,9 +1683,6 @@ OLD_FILES+=usr/share/examples/diskless/README.BOOTP
 OLD_FILES+=usr/share/examples/diskless/README.TEMPLATING
 OLD_FILES+=usr/share/examples/diskless/clone_root
 OLD_FILES+=usr/share/examples/dma/mailer.conf
-OLD_FILES+=usr/share/examples/drivers/README
-OLD_FILES+=usr/share/examples/drivers/make_device_driver.sh
-OLD_FILES+=usr/share/examples/drivers/make_pseudo_driver.sh
 OLD_FILES+=usr/share/examples/dwatch/profile_template
 OLD_FILES+=usr/share/examples/etc/README.examples
 OLD_FILES+=usr/share/examples/etc/bsd-style-copyright
@@ -1912,7 +1909,6 @@ OLD_DIRS+=usr/share/examples/bsdconfig
 OLD_DIRS+=usr/share/examples/csh
 OLD_DIRS+=usr/share/examples/diskless
 OLD_DIRS+=usr/share/examples/dma
-OLD_DIRS+=usr/share/examples/drivers
 OLD_DIRS+=usr/share/examples/dwatch
 OLD_DIRS+=usr/share/examples/etc
 OLD_DIRS+=usr/share/examples/etc/defaults