Add support for the h8300-linux target.

Add support for the h8300-linux target.

ld	* Makefile.am: (ALL_EMULATION_SOURCES): Add new emulations.
	* Makefile.in: Regenerate.
	* configure.tgt: Add h8300-*-linux
	* emulparams/h8300elf_linux.sh: Add new emulation.
	* emulparams/h8300helf_linux.sh: Likewise.
	* emulparams/h8300self_linux.sh: Likewise.
	* emulparams/h8300sxelf_linux.sh: Likewise.

bfd	* config.bfd: Add h8300-*-linux.
	* configure.ac: Add h8300_elf32_linux_vec.
	* configure: Regenerate.
	* elf32-h8300.c: Likewise.
	* targets.c(_bfd_target_vector): Likewise.

gas	* config/tc-h8300.c (line_separater_chars): Add a version for
	h8300-linux that includes a separator.
	(default_mach): New variable.
	(md_main): Use it.
	(md_longopts): Add '--march' option.
	(md_parse_option): Parse the new option.
	* config/tc-h8300.h (TARGET_FORMAT): Add elf32-h8300-linux.
	* configure.tgt: Add h8300-*-linux
	* doc/c-h8300.texi: Document --march.