This patch adds:

1) A new method Output::print_scheduling() that encapsulates the ir node printing on blocks
2) Modifying print_ideal_ir to use the print_scheduling() when there is a scheduling available
3) A new compiler phase MACH_ANALYSIS after the mach dependent optimizations.

Motivation:
This is used by the IR-test framework when testing optimizations on mach-nodes, and is a requirement to be able to test peephole-optimizations (because peephole-removed nodes are only removed from the scheduling, not from the graph.)

Having a method for print_scheduling() is also very useful when debugging.