Proper SXUNUSED() macro implementation.

include/ph7int.h

@@ -143,7 +143,7 @@ typedef sxi32(*ProcRawStrCmp)(const SyString *, const SyString *);
 
 #define SX_ADDR(PTR)    ((sxptr)PTR)
 #define SX_ARRAYSIZE(X) (sizeof(X)/sizeof(X[0]))
-#define SXUNUSED(P)	(P = 0)
+#define SXUNUSED(P)	((void)P)
 #define	SX_EMPTY(PTR)   (PTR == 0)
 #define SX_EMPTY_STR(STR) (STR == 0 || STR[0] == 0 )
 typedef struct SyMemBackend SyMemBackend;