Eliminate more 'scope of variable can be reduced' cppcheck style warnings

Eliminate more 'scope of variable can be reduced' cppcheck style warnings

* allchblk.c [MARK_BIT_PER_GRANULE] (setup_header): Move local variable
declarations to the inner scope where the variables are actually used.
* alloc.c [!SMALL_CONFIG] (GC_try_to_collect_inner,
GC_finish_collection): Likewise.
* alloc.c (GC_stopped_mark): Likewise.
* backgraph.c [MAKE_BACK_GRAPH] (add_edge): Likewise.
* darwin_stop_world.c [GC_DARWIN_THREADS] (GC_push_all_stacks,
GC_stop_world, GC_thread_resume): Likewise.
* dyn_load.c [USE_PROC_FOR_LIBRARIES] (sort_heap_sects): Likewise.
* dyn_load.c [ALPHA && OSF1 || HPUX] (GC_register_dynamic_libraries):
Likewise.
* dyn_load.c [DARWIN] (GC_dyld_image_add, GC_dyld_image_remove):
Likewise.
* extra/AmigaOS.c (GC_amiga_free_all_mem, GC_amiga_allocwrapper_any):
Likewise.
* extra/msvc_dbg.c (GetDescriptionFromAddress): Likewise.
* gcj_mlc.c [GC_GCJ_SUPPORT] (GC_core_gcj_malloc,
GC_gcj_malloc_ignore_off_page): Likewise.
* include/new_gc_alloc.h (single_client_gc_alloc_template::deallocate,
single_client_gc_alloc_template::ptr_free_deallocate,
single_client_traceable_alloc_template::deallocate,
single_client_traceable_alloc_template::ptr_free_deallocate): Likewise.
* malloc.c [THREADS] (GC_free_inner): Likewise.
* mark_rts.c (GC_add_roots_inner): Likewise.
* misc.c (GC_clear_stack): Likewise.
* os_dep.c [GWW_VDB] (GC_gww_read_dirty): Likewise.
* os_dep.c [MPROTECT_VDB] (GC_protect_heap): Likewise.
* os_dep.c [PROC_VDB] (GC_read_dirty): Likewise.
* os_dep.c [MPROTECT_VDB && DARWIN] (catch_exception_raise): Likewise.
* pthread_stop_world.c [GC_NETBSD_THREADS_WORKAROUND] (GC_start_world):
Likewise.
* pthread_support.c [!GC_NO_PTHREAD_SIGMASK] (pthread_sigmask):
Likewise.
* reclaim.c [!SMALL_CONFIG] (GC_reclaim_all): Likewise.
* tests/test.c (run_one_test): Likewise.
* tests/test.c [MACOS] (SetMinimumStack): Likewise.
* thread_local_alloc.c [THREAD_LOCAL_ALLOC] (return_single_freelist):
Likewise.
* typd_mlc.c (GC_make_descriptor): Likewise.
* win32_threads.c (GC_start_world, GC_CreateThread): Likewise.
* win32_threads.c [!GC_PTHREADS_PARAMARK] (GC_start_mark_threads_inner):
Likewise.
* win32_threads.c [!MSWINCE && !CYGWIN32] (GC_beginthreadex): Likewise.