ChangeLog: actually fixed make smoke, now stable
[gc] decruft -DMEMORY_DEBUG and DETAIL_MEMORY_DEBUG, add -D100

Check -D100 instead of DETAIL_MEMORY_DEBUG when -DMEMORY_DEBUG is enabled.
This way we can run -D101 and -D1 to get verbose and non-verbose GC tracings.

Add new MEMORY_DEBUG_DETAIL_2 macro for fprintf helpers all over.
Move common panic_failed_allocation into gc_private.h, maybe the other
common gc memory funcs also to save space.
Print avail sysmem on startup with -D1.
GH #1108
[core] enable Interp_debug_TEST and flags with flag combinations

Now you can check for multiple flags, e.g.
if (Interp_debug_TEST(interp,
       PARROT_MEM_STAT_DEBUG_FLAG | PARROT_GC_DETAIL_DEBUG_FLAG))
Was used only for single flags, so no changes for existing code.
Document the single flag limitation for the left-over trace_flags test.
There's no -t flag combination, like verbose yet.
[cage] unconst IO_VTABLE * vtables, -Wcast-qual cannot be suppressed

see e.g. https://stackoverflow.com/questions/13249756/explicit-ignore-warning-from-wcast-qual-cast-discards-attribute-const#comment38552597_13253997

2 remaining -Wcast-qual warnings for legacy API.
[gc] check -D1 in startup, add -D2xx MEM_DETAIL_DEBUG_FLAG

Print GS and Memory info on -D1.
Add seperate GC_DEBUG_DETAIL_2 tracer to seperate it from
MEM_DETAIL_DEBUG_FLAG tracing for every single alloc/free.
Document the two new -D100 and -D200 flags with --ccflags=-DMEMORY_DEBUG
[pmc] add Coroutine.mark with caller_seg

Coroutine.mark was just calling Sub.mark and missed to mark
the caller_seg. Do it now properly with inheritance.
Note that this does not fix GH #1109, which is a Coro in a wrong gen
[gc] Better -D1 printout. ChangeLog #1108

$ ulimit -Sv 640
$ ./parrot -D1
Free Memory: 8589934592
Memory via rlimit restricted to: 655360
GC nursery size: 2.0%
GMS GC threshold: 13107