Replace pointer relational comparisons with non-pointer ones

Replace pointer relational comparisons with non-pointer ones

* allchblk.c (GC_dump_regions, GC_allochblk_nth): Cast pointers to
word type in relational (less-greater) comparisons.
* alloc.c (GC_add_to_heap, GC_print_heap_sects, GC_expand_hp_inner):
Likewise.
* backgraph.c (ensure_struct, add_back_edges): Likewise.
* blacklst.c (GC_number_stack_black_listed): Likewise.
* checksums.c (GC_checksum, GC_check_dirty): Likewise.
* darwin_stop_world.c (GC_push_all_stacks): Likewise.
* dbg_mlc.c (GC_get_back_ptr_info, GC_print_smashed_obj,
GC_check_heap_block): Likewise.
* dyn_load.c (sort_heap_sects, GC_register_map_entries,
GC_register_dynlib_callback,
GC_register_dynamic_libraries_dl_iterate_phdr,
GC_register_dynamic_libraries, GC_cond_add_roots): Likewise.
* finalize.c (GC_ignore_self_finalize_mark_proc): Likewise.
* headers.c (GC_scratch_alloc, GC_install_counts, GC_remove_counts):
Likewise.
* include/private/gc_pmark.h (PUSH_OBJ, PUsH_CONTENTS_HDR,
GC_PUSH_ONE_STACK, GC_PUSH_ONE_HEAP, GC_mark_stack_empty): Likewise.
* include/private/gc_priv.h (MAKE_COOLER, COOLER_THAN): Likewise.
* mach_dep.c (GC_with_callee_saves_pushed): Likewise.
* malloc.c (calloc, free): Likewise.
* mark.c (GC_mark_some_inner, GC_mark_from, GC_steal_mark_stack,
GC_return_mark_stack, GC_do_local_mark, GC_mark_local, GC_push_all,
GC_push_selected, GC_push_all_eager, GC_push_marked1, GC_push_marked2,
GC_push_marked4, GC_push_marked, GC_push_unconditionally): Likewise.
* mark_rts.c (GC_is_static_root, GC_add_roots_inner,
GC_remove_roots_inner, GC_is_tmp_root, GC_exclude_static_roots_inner,
GC_push_conditional_with_exclusions, GC_push_all_register_sections,
GC_push_all_stack_sections, GC_push_all_stack_partially_eager,
GC_push_all_stack_part_eager_sections, GC_push_current_stack):
Likewise.
* misc.c (GC_clear_stack_inner, GC_clear_stack, GC_base,
GC_call_with_gc_active): Likewise.
* new_hblk.c (GC_build_fl_clear2, GC_build_fl_clear4,  GC_build_fl2,
GC_build_fl4, GC_build_fl): Likewise.
* os_dep.c (GC_enclosing_mapping, GC_text_mapping, tiny_sbrk,
GC_find_limit_openbsd, GC_skip_hole_openbsd, GC_find_limit_with_bound,
GC_get_main_stack_base, GC_get_stack_base, GC_least_described_address,
GC_register_root_section, GC_register_data_segments, GC_unmap_start,
GC_gww_read_dirty, GC_remove_protection, GC_protect_heap,
GC_unprotect_range, GC_read_dirty, GC_page_was_dirty,
GC_save_callers, GC_print_callers): Likewise.
* pcr_interface.c (GC_enumerate_block): Likewise.
* pthread_support.c (GC_is_thread_tsd_valid,
GC_segment_is_thread_stack, GC_greatest_stack_base_below,
GC_call_with_gc_active): Likewise.
* ptr_chck.c (GC_same_obj, GC_is_valid_displacement, GC_on_stack,
GC_is_visible): Likewise.
* reclaim.c (GC_reclaim_clear, GC_reclaim_uninit,
GC_disclaim_and_reclaim, GC_reclaim_check, GC_start_reclaim):
Likewise.
* tests/test.c (cons): Likewise.
* tools/setjmp_t.c (main): Likewise.
* typd_mlc.c (GC_typed_mark_proc): Likewise.
* win32_threads.c (GC_is_thread_tsd_valid, GC_call_with_gc_active,
GC_push_stack_for, GC_get_next_stack): Likewise.
* extra/msvc_dbg.c (GetDescriptionFromAddress,
GetDescriptionFromStack): Cast pointers to GC_ULONG_PTR in relational
comparisons.
* include/gc.h (GC_DATASTART, GC_DATAEND): Cast pointers to GC_word in
relational comparisons.
* misc.c (GC_init): Remove static assertion on ((ptr_t)-1 > 0) since
no longer required; add the comment.
* pcr_interface.c: Expand tabs to spaces.