dwarf2out: Remove unused text-based unwind entry points.

dwarf2out: Remove unused text-based unwind entry points.

The dwarf2out_cfi_label function is privatized, the
dwarf2out_def_cfa function is merged into its last user.
The others really are unused.

        * dwarf2out.c (dwarf2out_cfi_label): Make static.
        (dwarf2out_flush_queued_reg_saves): Make static.
        (dwarf2out_reg_save): Remove.
        (dwarf2out_return_save): Remove.
        (dwarf2out_return_reg): Remove.
        (dwarf2out_reg_save_reg): Remove.
        (dwarf2out_def_cfa): Merge into ...
        (dwarf2out_frame_init): ... here.
        * dwarf2out.h, tree.h: Remove declarations as necessary.

From-SVN: r175876