gdb/

gdb/
	Fix gdb.fortran/common-block.exp crash in PIE mode.
	* dwarf2read.c (new_symbol_full) <DW_TAG_common_block>: Use
	LOC_COMMON_BLOCK.
	* f-valprint.c (info_common_command_for_block): Expect
	LOC_COMMON_BLOCK in gdb_assert.
	* symtab.h (struct general_symbol_info): Update comment for the
	common_block member.
	(domain_enum): Extend comment for the COMMON_BLOCK_DOMAIN member.
	(enum address_class): New member LOC_COMMON_BLOCK.