fix build on non-linux

src/core/disk_ops/unistd/disk_unistd_global.c

@@ -59,15 +59,15 @@
 
 #ifndef HAVE_COPY_FILE_RANGE 
 #ifdef __NR_copy_file_range
-static loff_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
+static ssize_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
 		loff_t *off_out, size_t len, unsigned int flags)
 {
 	return syscall(__NR_copy_file_range, fd_in, off_in, fd_out,
 			off_out, len, flags);
 }
 #else
-static loff_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
-		loff_t *off_out, size_t len, unsigned int flags)
+static ssize_t copy_file_range(int fd_in, off_t *off_in, int fd_out,
+		off_t *off_out, size_t len, unsigned int flags)
 {
 	errno = ENOSYS;
 	return -1;