calls: Change return type of predicate function from int to bool

Also change some internal variables and some function arguments to bool.

gcc/ChangeLog:

    * calls.h (setjmp_call_p): Change return type from int to bool.
    * calls.cc (struct arg_data): Change "pass_on_stack" to bool.
    (store_one_arg): Change return type from int to bool
    and adjust function body accordingly.  Change "sibcall_failure"
    variable to bool.
    (finalize_must_preallocate): Ditto.  Change *must_preallocate pointer
    argument  to bool.  Change "partial_seen" variable to bool.
    (load_register_parameters):  Change *sibcall_failure
    pointer argument to bool.
    (check_sibcall_argument_overlap_1): Change return type from int to bool
    and adjust function body accordingly.
    (check_sibcall_argument_overlap):  Ditto.  Change
    "mark_stored_args_map" argument to bool.
    (emit_call_1): Change "already_popped" variable to bool.
    (setjmp_call_p): Change return type from int to bool
    and adjust function body accordingly.
    (initialize_argument_information): Change *must_preallocate
    pointer argument to bool.
    (expand_call): Change "pcc_struct_value", "must_preallocate"
    and "sibcall_failure" variables to bool.
    (emit_library_call_value_1): Change "pcc_struct_value"
    variable to bool.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Uros.