optimize method dispatch for lead/kw params.

similar idea to r67315, provide the following optimization
for method dispatch with lead and kw parameters.

(1) add a special branch to check passing kw arguments to
    a method which has lead and kw parameters.
    ex) def foo(x, k:1); end; foo(0, k:1)
(2) add a special branch to check passing no-kw arguments to
    a method which has lead and kw parameters.
    ex) def foo(x, k:1); end; foo(0)

For (1) and (2) cases, provide special dispatchers. For (2) case,
this patch only use the special dispatcher if all default
kw parameters are literal values (nil, 1, and so on. In other case,
kw->default_values does not contains Qundef) (and no required kw
parameters becaseu they don't pass any keyword parameters).

Passing keyword arguments with a hash object is not a scope of
this patch.

Without this patch, (1) and (2) cases use `setup_parameters_complex()`.
Especially, (2) seems frequent case for methods which extend a normal
usecase with keyword parameters (like: `exception: true`).

We can measure the performance with benchmark-driver:
  With methods: def kw k1:1, k2:2; end
                def m; end
  With the following binaries:
    clean-miniruby: unmodified trunk.
    opt_miniruby1: use special branches for lead/kw parameters.
    opt_miniruby2: use special dispatchers for lead/kw parameters.
    opt_cc_miniruby: apply step (2).
  Result with benchmark-driver:

                              m
     opt_miniruby2:  75222278.0 i/s
    clean-miniruby:  73177896.5 i/s - 1.03x  slower
     opt_miniruby1:  62466783.3 i/s - 1.20x  slower

                             kw
     opt_miniruby2:  52044504.4 i/s
     opt_miniruby1:  29142025.7 i/s - 1.79x  slower
    clean-miniruby:  20515235.4 i/s - 2.54x  slower

                      kw k1: 10
     opt_miniruby2:  26492219.5 i/s
     opt_miniruby1:  25409484.9 i/s - 1.04x  slower
    clean-miniruby:  20235113.7 i/s - 1.31x  slower

              kw k1: 10, k2: 20
     opt_miniruby1:  24159534.0 i/s
     opt_miniruby2:  23470527.5 i/s - 1.03x  slower
    clean-miniruby:  17822621.5 i/s - 1.36x  slower


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67333 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

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