b2 does not build using MSVC with Unicode support (/DUNICODE)

[mloskot]

The b2 driver code implicitly assumes use of ANSI version of Win32 API functions, e.g.

char buf[ 1024 ];
DWORD const ret = GetModuleFileName( NULL, buf, sizeof( buf ) );

Obviously, attempts to compile with cl /DUNICODE will fail due to char* to wchar_t* conversions as GetModuleFileName resolves to GetModuleFileNameW.

There either should be an early exit somewhere

#if defined(UNICODE) || defined(_UNICODE)
#error "Building with C run-time support for Unicode is not supported"
#endif

or ANSI variants of Win32 API functions should be preferred, change from GetModuleFileName to GetModuleFileNameA, etc.

[grafikrobot]

I like being explicit, and hence we should use the ANSI variants. At least until some future when we can make b2 support unicode.