Windows syslog() emulation: improve error messages

If syslog can't log to the Windows event log for some reason, instead of
just printing the log message to the console, include some explanatory
text about what went wrong.

(cherry picked from commit c492c90)

lib/win32/emu.cpp

@@ -1531,7 +1531,7 @@ void syslog(int loglevel, const char *frmt, ...)
 	assert(len >= 0);
 	if (len < 0) 
 	{
-		printf("%s\r\n", buffer);
+		printf("<syslog(): message too long> %s\r\n", buffer);
 		fflush(stdout);
 		return;
 	}
@@ -1543,7 +1543,7 @@ void syslog(int loglevel, const char *frmt, ...)
 
 	if (gSyslogH == INVALID_HANDLE_VALUE)
 	{
-		printf("%s\r\n", buffer);
+		printf("<syslog(): invalid handle> %s\r\n", buffer);
 		fflush(stdout);
 		return;
 	}