d3dx9_36/tests: Fix printing a NULL string

[Michael Stefaniuc]

Joerg-Cyril.Hoehle at t-systems.com wrote:
> Bruno Haible was so kind to provide the following test run results:
> 
> glibc          SIGSEGV
> MacOS X 10.5   (null)
> FreeBSD 6.4    (null)
> OpenBSD 4.9    (null)
> AIX 7.1        empty
> HP-UX 11.31    empty
> IRIX 6.5       (null)
> OSF/1 5.1      (null)
> Solaris 10     SIGSEGV
> Cygwin         (null)
> mingw          (null)
> 
> for printf("%s", NULL)
> 
> Looks like the next Coccinelle job will be to flag potential NULL pointers
> used in %s in logs, not the tests...
Not easily done with coccinelle as it doesn't looks into strings; those
are just string literal constants for it. Those could be processed in a
embedded python rule but the whole logic would need to be implemented there.

bye
	michael