Adds support to the RL78 port for linker relaxation affecting .debug sections.

Adds support to the RL78 port for linker relaxation affecting .debug sections.

gas	* config/tc-rl78.h (TC_LINKRELAX_FIXUP): Define.
	(TC_FORCE_RELOCATION_SUB_SAME): Define.
	(DWARF2_USE_FIXED_ADVANCE_PC): Define.

	* gas/lns/lns.exp: Add RL78 to list of targets using
	DW_LNS_fixed_advance_pc.

bfd	* elf32-rl78.c (RL78_OP_REL): New macro.
	(rl78_elf_howto_table): Use it for complex relocs.
	(get_symbol_value): Handle the cases when the info or status
	arguments are NULL.
	(get_romstart): Cache the status returned by get_symbol_value.
	(get_ramstart): Likewise.
	(RL78_STACK_PUSH): Generate an error message if the stack
	overflows.
	(RL78_STACK_POP): Likewise for underflows.
	(rl78_compute_complex_reloc): New function.  Contains the basic
	processing code for all RL78 complex relocs.
	(rl78_special_reloc): New function.  Provides special reloc
	handling for complex relocs.
	(rl78_elf_relocate_section): Use rl78_compute_complex_reloc.
	(rl78_offset_for_reloc): Likewise.

binutils* readelf.c (target_specific_reloc_handling): Add code to handle
	RL78 complex relocs.