* autoload.cc: Autoload CharToOemA.

* autoload.cc: Autoload CharToOemA.
* dcrt0.cc (dll_crt0_1): Translate command line to OEM if current codepage is
OEM.
* environ.cc: Add new option 'codepage' to CYGWIN environment variable.
* fhandler_clipboard.cc (fhandler_clipboard::read): Read clipboard in OEM mode
if current codepage is OEM.
* fhandler_console.cc (fhandler_console::read): Only translate console input if
current codepage is ANSI.
* fhandler_console.cc (fhandler_console::write_normal): Translate output data
if current codepage is ANSI.
* pinfo.cc (codepage_init): New function.  Setup current codepage from CYGWIN
environment variable and set codepage for file APIs.
* security.cc (read_sd): Translate file name to it if current codepage is OEM.
* winsup.h: (sys_wcstombs,sys_mbstowcs): Use current codepage for translations
between multibyte and widechar string and vice versa.