Get rid of obsolete code, most of it '#if 0'ed anyway.

Get rid of obsolete code, most of it '#if 0'ed anyway.
Mostly vestiges of Dave's long-gone instruction prefetching stuff.

arch/alpha/isa_traits.hh:
    Delete unused extractInstructionPrefetchTarget().
base/inifile.cc:
    Delete '#if 0' code
cpu/base_cpu.hh:
    Delete unused filterThisInstructionPrefetch() function.
cpu/exetrace.hh:
    Delete '#if 0' code (obsolete flags).

--HG--
extra : convert_revision : c8317f56ba0a0e568daa785825ee938584987bed