* machmode.h (mode_name): Constify a char*.

	* rtl.c (mode_name): Likewise.

	* genopinit.c (gen_insn): Use accessor macro, not `mode_name'.

	* optabs.c (init_libfuncs): Constify a char*.

	* print-tree.c (mode_name): Remove redundant declaration.
	(print_node): Use accessor macro, not `mode_name'.

	* reload1.c (dump_needs): Constify a char*.  Use accessor macro,
	not `mode_name'.
	(new_spill_reg): Constify a char*.

	* tree.c (mode_name): Remove redundant declaration.

From-SVN: r28783