missing type description for typedef to pointer value

missing type description for typedef to pointer value

If we evaluate an expression that results in a value that is a typedef
to pointer, then the debugger fails to print the type description
before printing the actual value:

    (gdb) print e.plan(1)
    $1 = 0x0

The expected output is:

    (gdb) print e.plan(1)
    $1 = (access integer) 0x0

gdb/ChangeLog:

        * ada-valprint.c (ada_value_print): Handle typedefs.

gdb/testsuite/ChangeLog:

        * gdb.ada/ptr_typedef: New testcase.