sanitize: pass correct size to memset()

We did not want a size of a pointer but instead size of the underlying
memory storage.

xmem.c

@@ -107,7 +107,7 @@ void * X_malloc( size_t size, char *in_file, int in_line )
 	BlockInLine[i] = in_line;
 	MemUsed += size;
 
-	memset(Pnt,0,sizeof(Pnt)); // this protects whole program against dirty memory
+	memset(Pnt,0,size); // this protects whole program against dirty memory
 
 	return Pnt;
 
@@ -137,7 +137,7 @@ void * X_calloc( size_t num,size_t size, char *in_file, int in_line )
 	BlockInLine[i] = in_line;
 	MemUsed += num * size;
 
-	memset(Pnt,0,sizeof(Pnt)); // this protects whole program against dirty memory
+	memset(Pnt,0,size); // this protects whole program against dirty memory
 
 	return Pnt;