Initial SCons-based build system. See www.scons.org.

Initial SCons-based build system.  See scons.org.
'cd build; scons' will build ALPHA/m5.debug.
Use e.g. 'scons KERNEL/m5.opt' to build other binaries.
Read the comments in build/SConstruct for more details.

base/traceflags.py:
    Take basename of generated cc/hh files from command line instead
    of hardwiring them.  Lets us call the script from a different
    directory and still have the files end up in the right place
    (e.g. "base/traceflags.py base/traceflags").

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extra : convert_revision : ee4dbb59040cf07590929275f6c1c01e8d4e00b4