Make for directories without makefiles

[warmerdam]

I get lots of messages about attempting a make in directories with no target, like:

make[3]: Entering directory `/home/warmerdam/pkg/ossim-trunk/ossim/src/ossim/video'
make[3]: *** No rule to make target `all'.  Stop.

While these don't cause the build to fail, they are confusing when investigating a real problem. Changing this:

DIRECTORIES=$(wildcard *)

to this:

DIRECTORIES=$(dir $(wildcard */Makefile))

in the Makefile. Perhaps this would be worth incorporating.

[warmerdam]

The above change might also mean the following tests can be simplified:

		if [ -d $$d ]; then \
			if [ "$$d" != "CVS" -a "$$d" != "."  -a "$$d" != "test_endian"  -a "$$d" != "test" -a "$$d" != "generator" -a "$$d" != ".obj" ]; then \
				(cd $$d; $(MAKE) all) ; \
			fi ; \
		fi ; \