Wrong type for 'Length result.

Wrong type for 'Length result.

Consider the following code:

   type Color is (Black, Red, Green, Blue, White);
   type Primary_Table is array (Color range Red .. Blue) of Boolean;
   Prim : Primary_Table := (True, False, False);

GDB prints the length of arrays in a fairly odd way:

   (gdb) p prim'length
   $2 = blue

The length returned should be an integer, not the array index type,
and this patch fixes this.

gdb/ChangeLog:

	* ada-lang.c (ada_evaluate_subexp): Set the type of the value
	returned by the 'Length attribute to integer.

testsuite/ChangeLog:

	* gdb.ada/tick_length_array_enum_idx: New testcase.