Use struct dwarf2_prop also for bounds.

2013-08-01  Keven Boell  <keven.boell@intel.com>

gdb/

	* dwarf2read.c (read_tag_string_type): rename
	macro names.
	* gdbtypes.h: use dwarf2_prop for bounds
	and rename macros accordingly.

Change-Id: Id4b108114e9eedeffe3c3d64cb9ba5e770b821ea
Signed-off-by: Keven Boell <keven.boell@intel.com>