Dear all,

the attached patch fixes a mis-handling of optional dummy arguments
passed to optional dummy arguments of procedures with the bind(c)
attribute.  When those procedures are expecting CFI descriptors,
there is no special treatment like a presence check necessary
that by default passes a NULL pointer as default.

The testcase tries to exercise various combinations of passing
assumed-length character between bind(c) and non-bind(c), which
apparently was insufficiently covered in the testsuite.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald