C2 Call nodes use several constant values. So far C2 does not
support placing these values in the constant table of the nmethod.

Among others, these constants are
 - the called address
 - the inline cache
 - values required by the C-calling convention (on PPC, env pointer
   and toc from function descriptor)

This change extends Call nodes so that they can issue constants
to the constant table.

- Extend adlc to add edge to MachConstantBaseNode if
  $constanttablebase is used in the specification.
- Extend Call nodes to deliver proper register mask to
  register allocation for this new input.
- Add method ins_num_consts() so that number of required
  constants can be specified in the call node.
- Extend output() so that it reserves space for the
  constants in the Calls, using ins_num_consts().


----------------------------

This is preparation for PPC64 integration: http://openjdk.java.net/jeps/175
This and following ppc64 changes will go into staging repository first and tested there: http://hg.openjdk.java.net/ppc-aix-port/stage/

As we basically redesigned this, it comprises two of the original patches:
http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/338e318f1e12/ppc_patches/0114_opto-hook_to_postprocess_matcher_output_platform_dependent.patch
http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/338e318f1e12/ppc_patches/0120_opto-constants_for_Call_nodes.patch