libctf, create: fix addition of anonymous struct/union members

libctf, create: fix addition of anonymous struct/union members

A Solaris-era bug causes us to check the offsets of types with no names
against the first such type when ctf_add_type()ing members to a struct
or union.  Members with no names (i.e. anonymous struct/union members)
can appear as many times as you like in a struct/union, so this check
should be skipped in this case.

libctf/
	* ctf-create.c (membcmp)  Skip nameless members.