0.8.13.78: Birds of Feather

0.8.13.78: Birds of Feather
            * Fix dladdr bogosities: test if dladdr is supported on
               the platform, and add an ldso_stub for it if so. This
               so that SBCL isn't dependant on the dladdr being at the
               same location at runtime as it was on the build-host.
               Move the dummy definition for FOREIGN-SYMBOL-IN-ADDRESS
               to target-load, so that backtraces on target will work
               before foreign.lisp is built. Clean up the real F-S-I-A
               definition to use the :os-provides-dladdr feature.
            * Fix manual bogosities: generate functions signalling
               UNSUPPORTED-OPERATOR-ERROR for SB-BSD-SOCKETS
               platform-dependant sockopts on platforms where they're
               not supported; make these functions have the normal
               doctrings. This so that manual building will work on
               non-Linux as well. Also clean up the .sbclrc examples
               slightly.