Fix ADD_DEFINITION in CMakeLists.txt for kFreeBSD

* CMakeLists.txt: Fix broken ADD_DEFINITION for kFreeBSD.
Fix CMakeLists.txt: do not override CMAKE_OSX_ARCHITECTURES

* CMakeLists.txt: Since latest OSX compiler (clang) provided by Xcode is
not accept "-arch ppc"; So if CMAKE_OSX_ARCHITECTURES is defined by
client, CMakeLists.txt should not force "ppc;i386;x86_64".
Update AUTHORS file
Remove barrett_diagram file duplicated by tree.html

* Makefile.direct (DOC_FILES): Remove doc/barrett_diagram entry.
* Makefile.dj (OTHER_FILES): Likewise.
* doc/doc.am (dist_pkgdata_DATA): Likewise.
* doc/barrett_diagram: Remove file (as the content is duplicated in
doc/tree.html).
Remove non-existing DISCARD_WORDS from GC data structure ASCII diagram

* doc/tree.html (picture): Remove DISCARD_WORDS (since always zero
and already removed from the code in gc-6.0alpha6).
Bump GC_collect_at_heapsize in GC_add_to_heap. In the normal case it is
recalculated straight after. But in the case where it's called directly
from alloc_mark_stack, it isn't. If the mark stack gets very large,
this can cause GC_should_collect to always return true, and
GC_alloc_large to get stuck in a loop calling GC_collect_or_expand.
Remove 'opp' local variable in GC_malloc_X
(code refactoring)

* alloc.c: Update comment (about free lists).
* fnlz_mlc.c (GC_finalized_malloc): Remove "opp" local variable
(replace *opp with <kind>freelist[lg]).
* gcj_mlc.c (GC_gcj_malloc, GC_gcj_malloc_ignore_off_page): Likewise.
* malloc.c (GC_malloc_atomic, GC_malloc, GC_malloc_uncollectable):
Likewise.
* mallocx.c (GC_malloc_atomic_uncollectable): Likewise.
* typd_mlc.c (GC_malloc_explicitly_typed,
GC_malloc_explicitly_typed_ignore_off_page,
GC_calloc_explicitly_typed): Likewise.
Fix ok_init assignment (missing cast) in GC_new_kind_inner

* misc.c (GC_new_kind_inner): Add cast from int to GC_bool for ok_init.
Eliminate redundant *flh check for null in GC_allocobj
(code refactoring)

* alloc.c (GC_allocobj): Do not check *flh twice if the value
is non-NULL (GC_new_hblk is not called thus *flh stays non-NULL in
that case).
Fix typo in GC_collect_or_expand comment

* alloc.c (GC_collect_or_expand): Fix a typo in comment ("setting").
Make heap growth more conservative after GC_gcollect_and_unmap call
(Consider heap size growth since latest GC_gcollect_and_unmap
invocation instead of absolute heap size value when computing amount
of extra memory blocks to add to heap in GC_collect_or_expand.)

* alloc.c (GC_heapsize_at_forced_unmap): New static variable.
* alloc.c (GC_gcollect_and_unmap): Store current heap size to
GC_heapsize_at_forced_unmap; add comment.
* alloc.c (GC_collect_or_expand): Change blocks_to_get computation
considering heap size growth since latest GC_heapsize_at_forced_unmap
call (instead of the absolute heap size value); do not call
GC_expand_hp_inner twice with same argument.
* include/private/gc_priv.h (_GC_arrays._heapsize): Refine comment.
Fix 'attribute declaration must precede definition' warning (clang-3.1)

* extra/gc.c: Include gc_inline.h explicitly before including mallocx.c
(to workaround "attribute declaration must precede definition" warning
reported by clang-3.1 for GC_generic_malloc_many); define
GC_PTHREAD_REDIRECTS_ONLY before including gc_pthread_redirects.h.
* include/gc_pthread_redirects.h (GC_dlopen, GC_pthread_sigmask,
GC_PTHREAD_CREATE_CONST, GC_pthread_create, GC_pthread_join,
GC_pthread_detach, GC_pthread_cancel, GC_pthread_exit): Do not declare
if GC_PTHREAD_REDIRECTS_ONLY defined (to workaround
"attribute declaration must precede definition" warning reported by
clang-3.1).
Remove extra trailing backslash in GC_collect_or_expand
(adjust code formatting)

* alloc.c (GC_collect_or_expand): Remove unnecessary trailing
backslash (in multi-line expression).
Remove hb_large_block field (use 1 extra bit of hb_flags instead)

* allchblk.c (setup_header): Use (hb_flags & LARGE_BLOCK) != 0
instead of hb_large_block.
* private/gc_pmark.h (PUSH_CONTENTS_HDR): Likewise.
* mallocx.c (GC_realloc): Likewise.
* include/private/gc_priv.h (struct hblkhdr): Remove hb_large_block;
define LARGE_BLOCK to access corresponding bit in hb_flags (only if
MARK_BIT_PER_GRANULE).
Fix LARGE_BLOCK value used for hb_flags
(fix commit a49b495)

* include/private/gc_priv.h (LARGE_BLOCK): Redefine to 0x20 (to avoid
collision with MARK_UNCONDITIONALLY defined in case of ENABLE_DISCLAIM).
Group all compact fields of GC_arrays to fit in single page

* include/private/gc_priv.h (struct hblkhdr): Reorder hb_inv_sz field
to reduce alignment gaps on 64-bit targets.
* include/private/gc_priv.h (struct _GC_arrays): Reorder
_composite_in_use, _atomic_in_use, _unmapped_bytes, _all_nils,
_trace_addr, _modws_valid_offsets, _root_index, _last_stack fields
so that to have all compact (small-sized) fields in one memory page.
Merge pull request #30 from Hoops/loop-in-GC_alloc_large

Loop in GC_alloc_large
Update AUTHORS file
Add API function to set/modify GC log file descriptor (Unix)

* include/gc.h (GC_set_log_fd): New API function declaration.
* misc.c (GC_set_log_fd): New function definition (except for OS/2,
MacOS, Win32/CE and Android).
Fix mark stack excessive growth during parallel mark
(The growth observed in applications that implement things like weak
hash tables and iterate over the members marking entries using the
supplied GC_MARK_AND_PUSH macro.)

When overflow is signaled, only set GC_mark_stack_too_small if we
are using the global mark stack.  In parallel mode, local mark stack
is used, so the global mark stack is grown by GC_return_mark_stack
mainly.

* mark.c (GC_signal_mark_stack_overflow): Do not set
GC_mark_stack_too_small if GC_parallel.