export some CallContext methods

[rurban]

Calling CallContext methods internally via the indirect PMC vtable route might be too slow. See http://wknight8111.blogspot.com/2009/10/optimizing-parrot.html

Benchmark this:

• export the internally needed CallContext vtable methods (not static) and use them in our PCC (src/call/*.c only)
• add a lib/Parrot/Pmc2c/PMC/CallContext.pm to special case it (if worthwile)
• inline the CallContext ATTR accessors to omit the obj check, because there cannot be an override for it, or fix the definition in the header itself

i.e.

/* Generated macro accessors for 'arg_flags' attribute of CallContext PMC. */
#define GETATTR_CallContext_arg_flags(interp, pmc, dest) \
    do { \
        if (!PObj_is_object_TEST(pmc)) { \
            (dest) = ((Parrot_CallContext_attributes *)PMC_data(pmc))->arg_flags; \
        } \
        else { \
            (dest) = VTABLE_get_attr_str(interp, \
                              pmc, Parrot_str_new_constant(interp, "arg_flags")); \
        } \
    } while (0)

=>

#define GETATTR_CallContext_arg_flags(interp, pmc, dest) \
            (dest) = PARROT_CALLCONTEXT(pmc)->arg_flags;

to get benchmark numbers just fix include/pmc/pmc_callcontext.h and src/pmc/callcontext.c manually

[rurban]

Merged with Release 6.7.0