Introduce KORNSHELL make variable to point
to the implementation of the Korn Shell.
Use $(SHELL) or $(KORNSHELL) explicitly for
make programs that do not automatically call
shell scripts from the current directory.
Patch from Pascal Stumpf <Pascal.Stumpf@cubes.de>
Most is just copied from the existing imake installation in
/usr/X11R6. Additionally:
* Allow overriding CDESharedRev, X11ProjectRoot and ProjectRoot
* Add a new define to be able to override MINCLUDESRC too
(this allows me to build CDE without symlinking any include directories)
