[pcc] inline pcc_add_invocant and its attr accessor
[pmc2c] Faster CallContext ATTR accessors + non-static for GH #1083

Omit the obj check in the CallContext ATTR accessors.

Put CallContext non-static decl into .h as they are not static anymore,
so that we can call them now directly internally in src/call/*.c
to avoid VTABLE redirection for those.

work together with Reini Urban
[pcc] use the direct CallContext methods GH #1083

and do not use the CallContext vtable methods anymore.
also inline one Continuation_set_pointer call.

in fill_params() it is safe to use CallContext directly, as
it assumes either NULL or CallContext, but never PMCNULL.

all tests still passing, 1.63% faster.

Signed-off-by: Reini Urban <rurban@cpanel.net>
ChangeLog for GH #1083
ChangeLog for GSOC final evaluation
Merge branch 'pcc-gh1083'

Tests on all machines pass, and on most machines it's a tiny perf. win.
Release 6.7.0 - Grey-headed Lovebird

This release is still very stable. It adds two code changes:
- find_codepoint: added more name aliases for perl6 (LF,FF,CR and NEL)
- Optimize internal pcc CallContext calls from VTABLE to direct calls
  and inline CallContext ATTR accessors to omit the obj check. [GH #1083]
fresh ChangeLog, release.json for the next release
use absolute execname when we can in pbc_to_exe

Before this patch it used ARGV[0], which only contains a name like 'perl6'
but not the path to the binary, when this binary is executed as 'perl6'
and found in PATH.
Now it will try to resolv the absolute path to the binary for certain
platforms and will fall back to ARGV[0] if that fails or if the platform
is not supported.
memcpy the correct string length
Merge pull request #1088 from FROGGS/master

use absolute execname when we can in pbc_to_exe
pbc_to_exe: add unistd.h and ChangeLog

GH #1088
[test] Update Pod::Simple to 3.28

fixes missing whiteline_handler method.
add =encoding handling.

GH #1089
[codingstd] fix various pod syntax errors

These errors arose with the updated Pod::Simple/Checker, added with GH #1089
[codingstd] fix GH #1090 5.8 crashes with DEBUGGING

3 =~ ///gsx substs cause perl5.8 with to crash at
t/codingstd/c_enum.t,
t/codingstd/c_macro_args.t and
t/codingstd/c_cppcomments.t when DEBUGGING is enabled.

Skip those tests then.
[codingstd] podchecker on new Pod/Simple/Search

fixes 2 podchecker errors
ChangeLog cleanup 6.8.0
[tools] declare _NSGetExecutablePath on APPLE for pbc_to_exe
Prepare for the 6.8.0 release.
[native_pbc] update fingerprints

to avoid TODO tests.
$ perl tools/dev/pbc_header.pl --update-fingerprint t/native_pbc/*.pbc
should be part of the release process.