[GRASS5] Alternate Build Mechanism

[Glynn Clements]

I've added an alternate build mechanism, which uses GNU make (maybe
other, but not tested). The main features are:

1. It allows building in a separate directory from the source.

2. It allows the use of a read-only source directory (although write
permission is required to generate the makefiles).

3. It's significantly simpler than the existing mechanism.

Usage instructions are in the file mk/README.

The existing build mechanism should be unaffected.

There is one feature regarding the use of yacc which could use further
testing. In order to allow y.tab.[ch] to be generated in the build
directory, I invoke yacc as:

	$(YACC) -b $(OBJARCH)/y -d foo.y

This works with both "bison -y" and Berkeley yacc, but I'm unsure
about other versions of yacc.

-- 
Glynn Clements <glynn.clements at virgin.net>