Add feature to output citations automatically based on configuration (#90)

This change adds a new file to m5out which is citations.bib.
This file will contain the citations to the papers which describe the
aspects of the gem5 simulator that the simulation uses. In other words,
each simulation configuration could generate a different bib file
referencing different works.

Each SimObject can now have a set of citations associated with it. After
the system is built (in `instantiate`), the citations.bib file is
created by parsing all SimObjects that have been instantiated and taking
the union of their associated citations.

This commit is not meant to add all citations, but to act as an example
for others to add more citations to gem5.

Change-Id: Icd5c46fd9ee44adbeec1fea162657f5716f7e5ef
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>

src/python/m5/simulate.py

@@ -51,6 +51,7 @@ from . import SimObject
 from . import ticks
 from . import objects
 from . import params
+from .citations import gather_citations
 from m5.util.dot_writer import do_dot, do_dvfs_dot
 from m5.util.dot_writer_ruby import do_ruby_dot
 
@@ -164,6 +165,8 @@ def instantiate(ckpt_dir=None):
     # a checkpoint, If so, this call will shift them to be at a valid time.
     updateStatEvents()
 
+    gather_citations(root)
+
 
 need_startup = True