usb-linux.c: fix warning with _FORTIFY_SOURCE CC usb-linux.o cc1: warnings being treated as errors usb-linux.c: In function 'usb_host_read_file': usb-linux.c:1204: error: ignoring return value of 'fgets', declared with attribute warn_unused_result make: *** [usb-linux.o] Error 1 Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>