Win: Fix build with Visual Studio 2010 (broken by 607b668ff96e40fdc749de9b1bb98e7f40c86d93) - Visual Studio 2010 apparently doesn't have the snprintf() inline function, so restore the macro that emulates that function using _snprintf_s(). - Explicitly include errno.h in strtest.c, since jinclude.h doesn't include it when building with Visual Studio.