notes for makefiles, cygwin, and windows

[nicholas]

Hello, if you are having problems with the demo/example makefiles, in
cygwin, on windows, you may need to export some environment
variables. This example assumes you have installed Native Client to c:
\nacl

From the cygwin shell, export the following environment variables:

export NACL_BIN_PATH=/cygdrive/c/nacl/googleclient/native_client/
tools_bin/windows/sdk/nacl-sdk/bin
export SEL_LDR=/cygdrive/c/nacl/googleclient/native_client/scons-out/
opt-win/staging/sel_ldr

The first tells the makefile where to locate nacl-gcc.
The second tells the makefile how to launch sel_ldr. By default the
distribution only contains the optimized build of sel_ldr. If you
have successfully built the debug version of sel_ldr, then this
override is not needed.

Exporting these environment variables on the command line will
override the makefile definitions for the life of the cygwin console.

This note applies to 'make' on cygwin, windows XP, Quake, Earth, Life,
Voronoi, and tone examples when building them with the makefile. It
does not apply to the SCons build system.

Thank you, -nicholas