corpus: make get_unreferenced_(function|variable)_symbols use the new symtab

Make the corresponding members an implementation detail of corpus::priv.
They get computed based on the new symtab whenever they are accessed
first with an atomic instantiation. That simplifies the implementation
and homogenizes the access to functions and variables. Sorting does not
need to be done as the symtab already gives a guarantee for that.

        * src/abg-corpus-priv.h (corpus::priv::unrefed_var_symbols): make
          private, mutable and optional.
          (corpus::unrefed_fun_symbols): Likewise.
          (corpus::priv::get_unreferenced_function_symbols): New method declaration.
          (corpus::priv::get_unreferenced_variable_symbols): Likewise.
        * src/abg-corpus.cc
          (corpus::priv::build_unreferenced_symbols_tables): Delete method.
          (corpus::priv::get_unreferenced_function_symbols): New method implementation.
          (corpus::priv::get_unreferenced_variable_symbols): Likewise.
          (corpus::get_unreferenced_function_symbols): Proxy call to corpus::priv.
          (corpus::get_unreferenced_variable_symbols): Likewise.

Reviewed-by: Giuliano Procida <gprocida@google.com>
Signed-off-by: Matthias Maennich <maennich@google.com>
Change-Id: Ie1ede717c03d9823cc4520a0b706f6e951429e27
2 files changed