Makefile modification to allow building optiboot in more environments.

Allows building within the Arduino Source tree, and within the Arduino
IDE tree, as well as using CrossPack on Mac.

Adds README.TXT to track arduino-specific changes (and documents the
new build options.)

This addresses Arduino issue:

  http://code.google.com/p/arduino/issues/detail?id=487

And optiboot issue

  http://code.google.com/p/optiboot/issues/detail?id=1

(which can be thought of as a subset of the Arduno issue.)

Note that the binaries produced after these Makefile changes (using any
of the compile environments) are identical to those produced by the
crosspack-20100115 environment on a Mac.
(cherry picked from commit 2d2ed324b48e709f59a002cb274ed60bb0ebc911)

0 files changed, 0 insertions, 0 deletions