Only use stride for final element type

Only use stride for final element type

A DWARF array type may specify a stride.  Currently, the DWARF reader
applies this stride to every dimension of an array.  However, this
seems incorrect to me -- only the innermost array ought to use the
stride, while outer arrays should compute a stride based on the size
of the inner arrays.  This patch arranges to apply the stride only to
the innermost array type.  This fixes a bug noticed when running some
Ada tests with -fgnat-encodings=minimal.

gdb/ChangeLog
2020-11-04  Tom Tromey  <tromey@adacore.com>

	* dwarf2/read.c (read_array_type): Only apply stride to innermost
	array.

gdb/testsuite/ChangeLog
2020-11-04  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/enum_idx_packed.exp: Add test.
	* gdb.ada/enum_idx_packed/foo.adb (Multi_Access):
	New variable.
	* gdb.ada/enum_idx_packed/pck.ads (Short)
	(Multi_Dimension, Multi_Dimension_Access): New types.