Log: make find_last_log_page() portable

this makes it work with platforms with a larger 'long'

ArduCopter/Log.pde

@@ -338,7 +338,7 @@ static int find_last_log_page(int bottom_page)
 {
 	int top_page = 4096;
 	int look_page;
-	long check;
+	int32_t check;
 
 	while((top_page - bottom_page) > 1) {
 		look_page = (top_page + bottom_page) / 2;
@@ -347,7 +347,7 @@ static int find_last_log_page(int bottom_page)
 
 		//Serial.printf("look page:%d, check:%d\n", look_page, check);
 
-		if(check == (long)0xFFFFFFFF)
+		if(check == (int32_t)~0)
 			top_page = look_page;
 		else
 			bottom_page = look_page;

ArduPlane/Log.pde

@@ -313,13 +313,13 @@ static int find_last_log_page(int bottom_page)
 {
 	int top_page = 4096;
 	int look_page;
-	long check;
+	int32_t check;
 
 	while((top_page - bottom_page) > 1) {
 		look_page = (top_page + bottom_page) / 2;
 		DataFlash.StartRead(look_page);
 		check = DataFlash.ReadLong();
-		if(check == (long)0xFFFFFFFF)
+		if(check == (int32_t)~0)
 			top_page = look_page;
 		else
 			bottom_page = look_page;