The recent support for missing external binaries does not show an error
message when a file is genuinely missing (i.e. it is missing but not
marked as 'external'). This means that when -m is passed to binman, it
will never report a missing file.
Fix this and add a test.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
