Fix issues proposed in Ivan's previous commit, etc.

Fix issues proposed in Ivan's previous commit, etc.

* disclaim.c -> {finalized_mlc.c, misc.c}: Move low-level code to misc.c and
the finalized object-kind to finalized_mlc.c.
* Makefile.am: Update accordingly.
* reclaim.c: Condition #include "gc_disclaim.h" and remove "register".
* include/gc_disclaim.h, include/private/gc_priv.h, finalized_mlc.c, misc.c:
Add GC_API, GC_CALL, and GC_CALLBACK.  Use typedefs for function pointers.
* tests/disclaim_test.c, tests/disclaim_bench.c: Fix portability and other
issues.

* include/gc_disclaim.h: Forward declare ...
* finalized_mlc.c: ... and export GC_finalized_objfreelist.
* thread_local_alloc.c (GC_destroy_thread_local): Return finalized
freelists though the same global.
* include/private/thread_local_alloc.h: Tweak (move array above comment).

* Makefile.dj, NT_MAKEFILE, NT_STATIC_THREADS_MAKEFILE,
NT_X64_STATIC_THREADS_MAKEFILE, NT_X64_THREADS_MAKEFILE, gc.mak,
windows-untested/vc60/gc.dsp, windows-untested/vc70/gc.vcproj,
windows-untested/vc71/gc.vcproj: Add include/gc_disclaim.h to various build
systems.  (Untested.)