Major rewrite to support cleaner method of dumping; a

Major rewrite to support cleaner method of dumping; a
static "bss" section is used for heap space during preload, and
bss data is now written to the proper section area when dumping.
(need_to_recreate_heap): Renamed to using_dynamic_heap.
(heap_index_in_executable): Obsolete variable removed.
(data_section): New variable.
(data_start_va): Renamed to data_start.
(data_start_file): Obsolete variable removed.
(bss_section):
(extra_bss_size):
(bss_section_static):
(bss_start_static):
(bss_size_static):
(extra_bss_size_static):
(heap_section): New variables.
(_start): Remove code based on old unexec method.  Call init_heap
to initialize sbrk heap.
(close_file_data): Update size of file when closing, so that
unexec doesn't have to work out exact size in advance.
(get_bss_info_from_map_file):
(get_section_size): Obsolete functions removed.
(rva_to_section): Fix minor bug, and add a work-around for a bug
in very old linkers.
(offset_to_section):
(relocate_offset): New functions.
(OFFSET_TO_RVA):
(RVA_TO_OFFSET):
(RVA_TO_SECTION_OFFSET):
(PTR_TO_RVA):
(PTR_TO_OFFSET):
(OFFSET_TO_PTR): New macros.
(get_section_info): Modify to support new unexec method;
determines address ranges in process that need dumping, and COFF
sections where data will be dumped.  Allows for static and global
bss data to be in separate ranges.  No longer relies on knowledge
of section names.
(copy_executable_and_dump_data_section): Renamed
copy_executable_and_dump_data.  Completely rewritten to copy
executable section by section, so that raw data areas can be
expanded to hold dumped data as necessary.  Allows for bss data to
be in same section as initialized data.  Reduces size of static
heap section to that used during preload.
(dump_bss_and_heap):
(w32_fatal_reload_error):
(read_in_bss):
(map_in_heap): Obsolete functions removed.
(unexec): Rounds off preload heap to nearest page rather than
virtual allocation unit.  Modified to match other changes.