[Ada] Array bound incorrectly printed for array indexed by enum subrange

Consider the following declarations:

   type Range_Type is (One, Two, Three);
   type Array_Type is array (Range_Type range One .. Two) of Integer;
   A : Array_Type := (1, 2);

Trying to print A can yield:

   (gdb) print a
   $1 = (one => 1, 2)

The bound of the first element should not have been printed, since
"one" is the first enumerate of type Range_Type. Similarly, with
the following declarations:

   type Array2_Type is array (Range_Type range Two .. Three) of Integer;
   A2 : Array2_Type := (2, 3);

GDB is failing to print the bound of the first element of "A2":

   (gdb) print a2
   $2 = (2, 3)

This is because the index type for both types Array_Type and Array2_Type
are subranges (by DWARF definition for arrays), of an anonymous subrange
type. When deciding whether to print the bound of the first element,
we handle subranges, but only up to one level. This patch enhanced
the code to handle any number of subrange levels.

gdb/ChangeLog:

        * ada-valprint.c (print_optional_low_bound): Get index_type's
        target type for as long as it is a TYPE_CODE_RANGE.

No testcase with this patch, but this will be tested via the testcase
of another patch, which uses the DWARF assembler to generate debugging
info for an array indexed by an enum.
Add missing empty line after declaration in ada-typeprint.c:print_range.

gdb/ChangeLog:

        * ada-typeprint.c (print_range): Add missing empty line
        after local declaration.
Remove unncessary function declarations in ada-typeprint.c.

These declarations are unncessary, and make it extra work when trying
to change the profile of one of these functions. This patch just
removes them.

Note that one of them (print_dynamic_range_bound), was improperly
indented.

gdb/ChangeLog:

        * ada-typeprint.c (print_array_type, print_choices, print_range)
        (print_range_bound, print_dynamic_range_bound, print_range_type):
        Remove declaration.
Try printing array range using the name of its index type

   type Char_Table is array (Character range Character'First .. Character'Last)
     of Natural;

Trying to print the type description of this type currently yields:

   (gdb) ptype char_table
   type = array ('["00"]' .. '["ff"]') of natural

Although technically correct, it seemed more useful to print the array
range as:

   (gdb) ptype char_table
   type = array (character) of natural

This patch implements this suggestion.

gdb/ChangeLog:

        * ada-typeprint (type_is_full_subrange_of_target_type):
        New function.
        (print_range): Add parameter bounds_prefered_p.  If not set,
        try printing range types using the name of their base type.
        (print_range_type): Add parameter bounds_prefered_p.
        Use it in call to print_range.
        (print_array_type, ada_print_type): Update calls to print_range
        and print_range_type.

gdb/testsuite/ChangeLog:

        * gdb.ada/array_char_idx: New testcase.
ada-lang.c: Really include "ui-out.h".

Currently, ada-lang.c pretends to include "ui-out.h" as follow:

    #ifdef UI_OUT
    #include "ui-out.h"
    #endif

However, UI_OUT is never defined as far as I can tell. This is confirmed
by rebuilding with a #error pragma inside the #ifdef UI_OUT block,
which never triggers.

Since this unit makes references to declarations from ui-out.h,
this patch simply removes the #ifdef/#endif condition.  This has not
been an error so far because "ui-out.h" indirectly gets included,
via one of the other .h files being included.

gdb/ChangeLog:

        * ada-lang.c: Remove "#ifdef UI_OUT" condition for including
        "ui-out.h".