Removed unneeded variable and function.
They were used with built-in configurations.
Commit 37c492b544dec2460fc2c16a3d66275cc0d4edc0 made them obsolete.
Removed useless command-line option.
Merge pull request #6 from greg-king5/forget-path

Removed useless command-line option.
Merge pull request #7 from greg-king5/config-buf

Removed unneeded variable and function.
Allow to build just the binaries or just the libraries from the top level Makefile.
Removed reference to CC65_HOME.

Now that we're pretty much independent from CC65_HOME
it doesn't make sense anymore to look for it in the Makefiles.

So rather dynamically check if there are "local" binaries in the
../bin directory. If there are "local" binaries use them - and
otherwise rely on "installed" binaries found in the path.