Extended main_type to store also Dwarf blocks and
location lists as low and high bound.

gdb:

2013-07-23  Keven Boell  <keven.boell@intel.com>

	* gdbtypes.h (main_type): Extended LONGEST low
	high and low bound by a union to store either
	a LONGEST value, a Dwarf block, or a Dwarf
	location list.

Change-Id: I850f5f20079bfdd7861cd7321b579453b24de783
Signed-off-by: Keven Boell <keven.boell@intel.com>