layers: Fix issue when sub-passes have diff attachment count.

In core_validation, if the attachment count between a primary
and secondary sub-pass was different, then it should treat
the shorter one as UNUSED.  So, if the longer one has the
attachment flags set to UNUSED, it shouldn't be an error.

Change-Id: I3647403551962ef522e7e2ba7ab10a5cb7466c52
1 file changed