Use integer as getopt_long returns integer

ARM chars are unsigned by default. getopt_long return 255 instead -1.
That will cause an endless loop for aarch64 platform.

Signed-off-by: Honggang Li <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Acked-by: Jonathan Toppins <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>

rdma-ndd/rdma-ndd.c

@@ -297,7 +297,7 @@ int main(int argc, char *argv[])
 			{ }
 		};
 
-		char c = getopt_long(argc, argv, "fh", long_opts, &opt_idx);
+		int c = getopt_long(argc, argv, "fh", long_opts, &opt_idx);
 		if (c == -1)
 			break;