Minor Sconscript edit ... mips decoder changes ... initialize NNPC and output fault name in simple cpu

SConscript:
    Separate Alpha EIO from syscall building for other architectures
arch/isa_specific.hh:
    change MIPS constant to 34k
arch/mips/isa/decoder.isa:
    Allow sll,ssnop,nop, and ehb to be determined through decoder using
    the different types of default cases
arch/mips/isa/formats/branch.isa:
    Delete debug code
arch/mips/isa/formats/noop.isa:
    add a Nop format
arch/mips/isa_traits.hh:
    use constants instead of enums
arch/mips/process.cc:
    point to the correct header file
cpu/simple/cpu.cc:
    Output the actual fault name
sim/process.cc:
    Inititalize NNPC

--HG--
extra : convert_revision : adb0026dfad25b14c98fb03c98bfe9c681bba6f8

SConscript

@@ -248,16 +248,21 @@ turbolaser_sources = Split('''
 
 # Syscall emulation (non-full-system) sources
 syscall_emulation_sources = Split('''
-
-	encumbered/eio/exolex.cc
-	encumbered/eio/libexo.cc
-	encumbered/eio/eio.cc
         kern/linux/linux.cc
         kern/tru64/tru64.cc
 	sim/process.cc
 	sim/syscall_emul.cc
         ''')
 
+alpha_eio_sources = Split('''
+	encumbered/eio/exolex.cc
+	encumbered/eio/libexo.cc
+	encumbered/eio/eio.cc
+        ''')
+
+if env['TARGET_ISA'] == 'ALPHA_ISA':
+    syscall_emulation_sources += alpha_eio_sources
+    
 memtest_sources = Split('''
 	cpu/memtest/memtest.cc
         ''')