Fix a main/sal/qa/osl/mutex build error on MacOS.

Found by: Pathangi Janardhanan Jatinshravan <JATINSHR001 at e dot ntu dot edu dot sg>
Patch by: Pathangi Janardhanan Jatinshravan <JATINSHR001 at e dot ntu dot edu dot sg>
Review by: me

sal/qa/osl/mutex/osl_Mutex.cxx

@@ -727,7 +727,7 @@ namespace osl_ClearableGuard
         TimeValue aTimeVal_after;
         osl_getSystemTime( &aTimeVal_after );
         sal_Int32 nSec = aTimeVal_after.Seconds - aTimeVal_befor.Seconds;
-        printf("nSec is %"SAL_PRIdINT32"\n", nSec);
+        printf("nSec is %" SAL_PRIdINT32"\n", nSec);
 
         myThread.join();