gdb/solib: make solib_ops::in_dynsym_resolve_code optional

Two solib ops implementations have dummy implementations for the
in_dynsym_resolve_code callback.  Make it optional, to avoid this.

Change-Id: I786776fb82ce1b96335a97713fbfe8074c84c00c
Reviewed-By: Guinevere Larsen <guinevere@redhat.com>
3 files changed