Added pass framework

The patch adds a Middle-End pass system and normalizes the current
 passes into the pass framework.

Passes have:
 - A start, work, and end functions.
 - A gate to determine to apply the pass.
 - Can provide a CFG dump folder.

mir_dataflow.cc, mir_graph.cc, mir_optimization.cc, ssa_transformation.cc:
 - Changed due to moving code into bb_optimizations.cc.
 - Moved certain functions from private to public due to needed from the passes.

pass.cc, pass.h:
 - Pass base class

pass_driver.cc, pass_driver.h:
 - The pass driver implementation.

frontend.cc:
 - Replace the function calls to the passes with the pass driver.

Change-Id: I88cd82efbf6499df9e6c7f135d7e294dd724a079
Signed-off-by: Jean Christophe Beyler <jean.christophe.beyler@intel.com>
13 files changed