[examples] enable regexdna.pir argv to allow gdb debugging

we now accept an optional filename arg to regexdna.pir
to study GC write barrier crashes with
gdb --args ./parrot examples/shootout/regexdna.pir examples/shootout/regexdna.pir_input
prepare ChangeLog for 6.4.0
[test] t/dynoplibs/debug.t - Skip debug_break on darwin also. See GH#1071
Prepare for the 6.4.0 release.
[config] fix failing ICU headers probes on multi-arch

We must not die when perl does not find the icuheaders.
cc needs to find it, and it does it in the probe if they are
in the proper cc searchdir.

icu-config does not store the full headerpath, only pkg-config.
Fixes [GH #1014] on debian/ubuntu
Merge branch 'rurban/icuheaders-gh1014'

Confirmed ok by pmichaud on Kubuntu 14.04, and also tested ok on solaris
[opengl] Fix BSD problem which does not define __APPLE__

Fix opengl on bsd which does not have __APPLE__ defined as 0.
freeglut from 2.0 to at least 2.8 relies on that define.
Fixes [GH #1070].
[pmc] minor optimization in Integer_multi_i_add_Complex

Deteced by Chirag++ and pmc2c.
Do not compute SELF.get_integer() twice and remove UNSUED(a).
Do the same for the default case below.
[pmc] oops, undo the previous optimization

it broke the integer test 39 add complex number.
Just remove the first duplicate SELF.get_integer call, and UNUSED(a)
[imcc] regenerated imclexer.c with latest flex

use yy_size_t len instead of int
[native_pbc] update fingerprints to unTODO tests

perl tools/dev/pbc_header.pl --update-fingerprint t/native_pbc/*.pbc
as per release_manager_guide
--gc=inf: fix t/op/gc.t and mention gms in Configure --help

gc_type = INF should skip the first gc tests
add local .perldb helper to .gitignore/MANIFEST.SKIP

so that git clean -dxf will not wipe it.
Improve pmc2c deps for PMC/$class.pm libs

depends only on the really used deps.
also sort the deps to generate comparable Makefile
[gc] add MEMORY_DEBUG support to the GMS gc

fix and enable -DMEMORY_DEBUG for the GMS gc,
add DETAIL_MEMORY_DEBUG lines for all sanity checked PMCs,
and add a single MEMORY_DEBUG line when write_barrier'ing a PMC

we never caught up with the change from the List_Item_Header iterator
to POINTER_ARRAY_ITER.
[gc] add MEMORY_DEBUG support to the GMS gc

fix and enable -DMEMORY_DEBUG for the GMS gc,
add DETAIL_MEMORY_DEBUG lines for all sanity checked PMCs,
and add a single MEMORY_DEBUG line when write_barrier'ing a PMC

we never caught up with the change from the List_Item_Header iterator
to POINTER_ARRAY_ITER.
Fixes GH issue #1073
[pmc2c] inline gc write barriers into vtable methods

:no_wb detection of :manual_wb, allow RETURN(decl var) also for VTABLE methods

add_write_barrier() now calls Parrot::Pmc2c::PCCMETHOD::rewrite_RETURNS.
Also add automatic WB for 0 or 1 return statements in the method body.
Other need either a RETURN or :manual_wb or :no_wb annotations.

Set manual_wb for :no_wb and PARROT_GC_WRITE_BARRIER in --dump
Detect it now earlier, in the parser

Missing write barriers typically cause the following errors:
t/examples/shootout.t: 16 examples/shootout/regexdna.pir SEGV
t/op/gc.t
t/pmc/*.t
[pmc] partially use new WB markers
[pmc] GSOC start. arrayiterator :no_wb, removed unnecessary :manual_wb

Start of GSOC 2014 work. Task 1: improve GC write barriers.
See GH issue #1069
[pmc] callcontext: manual WBs for shift_pmc & shift_string