* core.c (core_sym_class): Ignore symbols without BSF_FUNCTION

    * core.c (core_sym_class): Ignore symbols without BSF_FUNCTION
        set if ignore_non_function is set.
        * gprof.h (ignore_non_functions): Declare.
        * gprof.c (ignore_non_functions): Define.
        (long_options): Add "ignore-non-functions".
        (usage): Add new options.
        (main): Recognize "-D" and "--ignore-non-functions" option.
So we can get more accurate information on Solaris, HPUX and other
systems that can uniquely identify function symbols.