Ada: Print bounds/length of pointer to array with dynamic bounds

Ada: Print bounds/length of pointer to array with dynamic bounds

Trying to print the bounds or the length of a pointer to an array
whose bounds are dynamic results in the following error:

    (gdb) p foo.three_ptr.all'first
    Location address is not set.
    (gdb) p foo.three_ptr.all'length
    Location address is not set.

This is because, after having dereferenced our array pointer, we
use the type of the resulting array value, instead of the enclosing
type.  The former is the original type where the bounds are unresolved,
whereas we need to get the actual array bounds.

Similarly, trying to apply those attributes to the array pointer
directly (without explicitly dereferencing it with the '.all'
operator) yields the same kind of error:

    (gdb) p foo.three_ptr'first
    Location address is not set.
    (gdb) p foo.three_ptr'length
    Location address is not set.

This is caused by the fact that the dereference was done implicitly
in this case, and perform at the type level only, which is not
sufficient in order to resolve the array type.

This patch fixes both issues, thus allowing us to get the expected output:

    (gdb) p foo.three_ptr.all'first
    $1 = 1
    (gdb) p foo.three_ptr.all'length
    $2 = 3
    (gdb) p foo.three_ptr'first
    $3 = 1
    (gdb) p foo.three_ptr'length
    $4 = 3

gdb/ChangeLog:

        * ada-lang.c (ada_array_bound): If ARR is a TYPE_CODE_PTR,
        dereference it first.  Use value_enclosing_type instead of
        value_type.
        (ada_array_length): Likewise.

gdb/testsuite/ChangeLog:

        * gdb.dwarf2/dynarr-ptr.exp: Add 'first, 'last and 'length tests.