Convert macros in op.c to inline functions.

[schwern]

Candidates include...

• OpTYPE_set
• DEFER_OP
• POP_DEFERRED_OP
• INIT_OPSLOT
• RETURN_UNLIMITED_NUMBER
• DEFER
• IS_AND_OP
• IS_OR_OP
• HV_OR_SCALARHV
• MAX_ARGS_OP
• retsetpvs

These should all be only used by op.c, so you can modify them if you like. They should be replaced with static inline functions with the name lower cased. There should be no need to put them into embed.fnc.

For example...

#define IS_AND_OP(o)   (o->op_type == OP_AND)

Becomes...

static inline bool is_and_op(OP *o) { return o->op_type == OP_AND }

But as @johndeppe pointed out, IS_AND_OP(op) and IS_OR_OP(op) are just OP_TYPE_IS_NN(op, OP_AND) and OP_TYPE_IS_NN(op, OP_OR). They're used very infrequently, they're poorly documented, so it's better to delete them and use OP_TYPE_IS_NN().

Remember to...

• Use the inline branch
• One macro per commit.
  • Use your judgement if they're small.
• Run at least "make -j5 minitest" for each commit.
• Make sure the macro has no side effects.
• Preserve the macro's visibility (or lack thereof).
  • That means declare it static.
• grep -r MACRO_NAME to make sure nothing else is using it.
  • There shouldn't be. If there is, please comment below and we'll figure it out.
• Replacement functions should be declared static inline and the name lower cased.
  • #define IS_AND_OP(o) becomes static inline is_and_op(OP *o)

You don't have to do them all to make a pull request.