This has large memory savings, test prog,
perl -MTest::More -e"system 'pause'"
before 2196KB Private Bytes Win 7 32 bit to after 2092KB.

-On a CHEK the refcount is a U32 for memory savings on 64 bit CPUs while
 SHEKs are Size_t for refcount because of HE struct, on 32 bit Size_t and
 U32 happen to be the same thing, if there is future integration the
 refcount members will have to be the same type, then duping a SHEK or
 a CHEK is the same code, except that HVhek_COMPILING controls whether to
 aquire OP_REFCNT_LOCK before touching the ref count, in the future with
 atomic operations, the refcount can be manipulated with atomic operations
 regardless if it is a SHEK or CHEK since OP_REFCNT_LOCK lines were removed
-TODO figure out how to do static const CHEKs, hash member must be 0
 since its process specific randomized (rurban's B stores HEKs in RW static
 memory and fixes up the hash #s at runtime), add test and branch
 so that refcount isn't read and written or passed to PerlMemShared_free
 if static flag is on inidicating static const CHEK
-TODO Perl_newGP uses CHEKs not CopFILE, no memcpy and add _< that way
-TODO optimize the former alloca to smallbuf or Safefree or savestack
 newx free

Test more rare edge cases

This is #7 of a small series of commits to refactor INPUT keyword
handling.

The main job of parsing an INPUT line is to extract any information on
that line and use it to update the associated Param object (which was
likely created earlier when the XSUB's signature was parsed).

This commit makes that information also be stored in new fields in the
INPUT_line object. These new fields aren't currently used for anything,
but they could in principle become useful if options for deparsing or
exporting were added to ParseXS.

This is #7 of a small series of commits to refactor OUTPUT keyword
handling.

For OUTPUT_line, move, from the parse() method to the as_code() method,
the bit which checks for RETVAL and causes its "push return value on
stack" C code to be emitted later. Also, add a long comment explaining
why this delay is required.

The existing code in parse() worked purely by chance: it was just
returning (without a value) if the parameter name was RETVAL. This was a
hangover from moving the existing code from OUTPUT_handler() into a Node
parse() method. By returning undef, it was signalling to the caller that
the parse of the line failed, and so the subsequent call to as_code()
was skipped. Instead, indicate that the parse was successful, and have
as_code() skip RETVAL.