scons: Switch from the print statement to the print function.

Starting with version 3, scons imposes using the print function instead
of the print statement in code it processes. To get things building
again, this change moves all python code within gem5 to use the
function version. Another change by another author separately made this
same change to the site_tools and site_init.py files.

Change-Id: I2de7dc3b1be756baad6f60574c47c8b7e80ea3b0
Reviewed-on: https://gem5-review.googlesource.com/8761
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>

scons: add slicc and ply to sys.path and PYTHONPATH so everyone has access

Microcode: Fix a silent typo error in the microcode assembler.

Microcode: Fix a very old bug with parsing external labels in microcode.

Microassembler: Pass the actual mnemonic used to the macroop add_micro function

X86: Make the microassembler accept lines which are just labels.
The labels on these lines will be associated with whatever the next microop
is.

Fix a problem where part of a microops parameters might be interpretted as an "ID", and also added support for symbols.

Comment out some unnecessary debug statements.

Make an error message a little more descriptive.

Fix up param regular expression to not duplicated the escaping \ and to pair up \s correctly.

Clean things up

Add rom based macroops into the macroop dict instead of dropping them on the floor

Do something with ROM based macroops

Make directives take parameters and use the directive function and not it's name

Handle comments

Early micro assembler

src/arch/micro_asm.py:
Micro assembler
src/arch/micro_asm_test.py:
Test script for the micro assembler. This probably should go somewhere else eventually.