crt: msvcrt.def.in: Fix _swprintf/_vswprintf symbol aliases

Symbols _swprintf and _vswprintf were added in Windows Vista and have same
meaning as symbols without leading underscore in msvcrt.dll. These symbols
(both with and without leading underscore) differs from C99 variant as they
do not take maxlen parameter.

For compatibility with pre-Vista systems, which are x86-only, define
_swprintf and _vswprintf symbols on I386 and X64 as aliases to swprintf and
vswprintf.

Signed-off-by: LIU Hao <lh_mouse@126.com>