(malloc, free, realloc, calloc): Rename if

(malloc, free, realloc, calloc): Rename if
USE_CRT_DLL is defined, so Emacs can use GNU malloc even though it
cannot override the CRT malloc.
(_WINSOCK_H): Define to prevent normal winsock
definitions from being used.
(sys_nerr): Provide default definition.
(strdup, strupr, strnicmp, stricmp, tzset, tzname): Map to same
name with _ prepended.
(NSIG): Define if not known.
(get_emacs_configuration): Provide extern declaration.
(get_emacs_configuration_options): Provide extern declaration.
(EMACS_CONFIG_OPTIONS): Call get_emacs_configuration_options.