patmos: Boilerplate for single-path if-converter
Backported MachinePostDominators from 3.2
Merge branch 'master' into singlepath
Preliminary setup for single-path conversion

* Capable to handle a simple DAG (no loops yet)
* Two phased approach
  - before RA: predicate,
  - after RA: reduce (linearize blocks)
* Dependence to LLIR passes:
  - merge return
  - lower switch
singlepath: fix placement of SP pseudos

* setting kill flag properly
singlepath: added support for pred initialization
singlepath: refactored methods, only one init
singlepath: support for mbb merging at reduce
Moved SinglePath conversion to PreSched2
Merge branch 'master' into singlepath
Merge branch 'singlepath' into singlepath2
Easier obtaining of FrameLowering in PatmosRegisterInfo
flags added to PSET, PCLR
Merge branch 'master' into singlepath

Conflicts:
	lib/Target/Patmos/PatmosTargetMachine.cpp
Merge branch 'singlepath' into singlepath2

Conflicts:
	lib/Target/Patmos/PatmosTargetMachine.cpp
Construction of SPNode tree
Single-Path order of MBBs, with loops
single-path: control dependence for entry edge
single-path: initialization of entry edge (p0)
Refactoring SinglePathInfo to a proper pass