Declare and use __FB_COMPILER_CRT__setmode, __FB_COMPILER_CRT__fileno

Reduce a number of compiler warnings [MSVC8+]

[Source]

extern\icu\source\extra\uconv\uconv.cpp
 - ConvertFile::convertFile
 - main
   - [uses] __FB_COMPILER_CRT__setmode
   - [uses] __FB_COMPILER_CRT__fileno