Suppress output when running unit tests.

This does two things:
1) Now does not output to debug.log if -printtodebugger flag is passed
2) Unit tests set -printtodebugger so only test results are output to stdout

Note that -printtodebugger only actually prints to the debugger on Windows.

src/util.cpp

@@ -204,7 +204,7 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
         ret = vprintf(pszFormat, arg_ptr);
         va_end(arg_ptr);
     }
-    else
+    else if (!fPrintToDebugger)
     {
         // print to debug.log
         static FILE* fileout = NULL;