Adding a more correct trim function prototype to the struct of block device

operations.

buse.c

@@ -124,7 +124,7 @@ int buse_main(int argc, char *argv[], const struct buse_operations *aop, void *u
                 aop->flush();
                 break;
             case NBD_CMD_TRIM:
-                aop->trim();
+                aop->trim(from, len);
                 break;
             default:
                 assert(0);

buse.h

@@ -8,7 +8,7 @@ struct buse_operations {
     int (*write)(const void *buf, u_int32_t len, u_int64_t offset);
     int (*disc)();
     int (*flush)();
-    int (*trim)();
+    int (*trim)(u_int64_t from, u_int32_t len);
 
     u_int64_t size;
 };