Preparation work to convert the hppa targets to multiarch partial.

    Preparation work to convert the hppa targets to multiarch partial.

        * hppa-tdep.c: Add new functions replacing macro bodies from
        config/pa/tm-hppa.h. These function will be used to initialize
        the gdbarch structure. Import some comments from tm-hppa.h,
        and place them where appropriate, to avoid loosing them when
        we cleanup this file.
        (hppa_reg_struct_has_addr): New function.
        (hppa_inner_than): New function.
        (hppa_stack_align): New function.
        (hppa_pc_requires_run_before_use): New function.
        (hppa_instruction_nullified): New function.
        (hppa_register_byte): New function.
        (hppa_register_virtual_type): New function.
        (hppa_store_struct_return): New function.
        (hppa_cannot_store_register): New function.
        (hppa_frame_args_address): New function.
        (hppa_frame_locals_address): New function.
        (hppa_smash_text_address): New function.
        (hppa_coerce_float_to_double): New function. Requires the inclusion
        of "language.h".

        * Makefile.in (hppa-tdep.o): Add dependency on language.h.

        * tm-hppa.h (REG_STRUCT_HAS_ADDR): Change the definition of this
        gdbarch-eligible macro to a call to the new associated function
        created in hppa-tdep.c.
        (INNER_THAN): Likewise.
        (STACK_ALIGN): Likewise.
        (PC_REQUIRES_RUN_BEFORE_USE): Likewise.
        (INSTRUCTION_NULLIFIED): Likewise.
        (REGISTER_BYTE): Likewise.
        (REGISTER_VIRTUAL_TYPE): Likewise.
        (STORE_STRUCT_RETURN): Likewise.
        (CANNOT_STORE_REGISTER): Likewise.
        (FRAME_ARGS_ADDRESS): Likewise.
        (FRAME_LOCALS_ADDRESS): Likewise.
        (SMASH_TEXT_ADDRESS): Likewise.
        (COERCE_FLOAT_TO_DOUBLE): Likewise.
        (ABOUT_TO_RETURN): Delete, as no longer used.