Change child_ to win32_ throughout.

Change child_ to win32_ throughout.
* win32-nat.c (win32_ops): New variable.
(win32_so_ops): Ditto.
(psapi_get_dll_name): Make function static.
(struct so_stuff): Delete.
(struct lm_info): New struct.
(solib_start, solib_end): Redefine as struct so_list.
(safe_symbol_file_add_stub): Use so_list rather than so_stuff.
(register_loaded_dll): Ditto.  Special-case ntdll.dll.  Fill in lm_info field
of so_list with information previously stored in so_stuff.
(get_image_name): Make function static.
(max_dll_name_len): Make variable static.
(win32_free_so): New function.
(win32_current_sos): Ditto.
(win32_relocate_section_addresses): Ditto.
(handle_unload_dll): Use so_list rather than so_stuff.  Call free_so to delete
shared library.
(solib_address): Delete function.
(child_solib_loaded_library_pathname): Ditto.
(win32_clear_solib): Rename from child_clear_solibs.  Use so_list rather than
so_stuff.  Just clear win32-specific stuff.
(get_relocated_section_addrs): Delete.
(solib_symbols_add): Ditto.
(info_dll_command): Make static.  Use lm_info field from so_list to retrieve
load address.
(fake_create_process): Make function static.
(win32_xfer_memory): Ditto.
(win32_kill_inferior): Ditto.
(win32_resume): Ditto.
(cygwin_pid_to_str): Ditto.
(do_initial_win32_stuff): Use win32_ops rather than deprecated_child_ops.
(child_detach): Ditto.
(win32_mourn_inferior): Ditto.
(_initialize_win32_nat): Ditto.
(init_win32_ops): Ditto.  Fill out win32_so_ops and set current_target_so_ops
to win32_so_ops.
(core_dll_symbols_add): Delete.
(map_single_dll_code_section): Ditto.
(dll_code_sections_add): Ditto.
(core_section_load_dll_symbols): Ditto.
(child_solib_add): Ditto.