* cygheap.cc (cygheap_init): Set Cygwin default locale values.
* cygheap.h (struct cygheap_locale): New structure.
(struct user_heap_info): Add cygheap_locale member locale.
* dcrt0.cc (dll_crt0_1): Revert to calling _setlocale_r so that only
the applications locale is reverted to "C".
* environ.cc (environ_init): Remove unused got_lc variable.
* fhandler.h (class dev_console): Remove now unsed locale variables.
* fhandler_console.cc (fhandler_console::get_tty_stuff): Remove
setting dev_console's locale members.
(dev_console::con_to_str): Use internal locale settings. Default to
__ascii_wctomb if charset is "ASCII".
(fhandler_console::write_normal): Ditto.
* strfuncs.cc (__ascii_wctomb): Drop declaration.
(__db_wctomb): Use fixed value 2 instead of not
necessarily matching MB_CUR_MAX.
(__eucjp_wctomb): Use 3 instead of MB_CUR_MAX.
(sys_cp_wcstombs): Remove special case for "C" locale.
(sys_wcstombs): Implement here. Use internal locale data stored on
cygheap.
(sys_cp_mbstowcs): Remove special case for "C" locale.
(sys_mbstowcs): Implement here. Use internal locale data stored on
cygheap.
* syscalls.cc (internal_setlocale): New function to set cygheap locale
data and to reset CWD posix path.
(setlocale): Just call internal_setlocale from here if necessary.
* wchar.h (__ascii_wctomb): Declare.
(sys_wcstombs): Don't define inline, just declare.
(sys_mbstowcs): Ditto.