Replace xmalloc with stat_alloc in ld parser

Replace xmalloc with stat_alloc in ld parser

A few place dealing with ld script handling made some attempt to free
memory, but this was generally ignored and would be quite a lot of
work to implement.  Instead, use the stat_obstack rather than
mallocing in many more cases.

	* ldexp.c (exp_get_fill): Use stat_alloc for fill.
	* ldfile.c (ldfile_try_open_bfd): Don't free yylval fields.
	* ldgram.y: Replace xmalloc with stat_alloc throughout.
	* ldlang.c (stat_memdup, stat_strdup): New functions.
	(ldirname): Use stat_memdup.  Don't strdup ".".
	(output_section_callback_sort): Use stat_alloc.
	(output_section_callback_tree_to_list): Don't free.
	(lang_memory_region_lookup): Use stat_strdup.
	(lang_memory_region_alias): Likewise.
	(add_excluded_libs): Use stat_alloc and stat_memdup.
	(ldlang_add_undef, ldlang_add_require_defined): Use stat_strdup.
	(lang_add_nocrossref, lang_leave_overlay): Use stat_alloc.
	(realsymbol): Use stat_strdup for return value and always
	free symbol.
	(lang_new_vers_pattern, lang_new_vers_node): Use stat_alloc.
	(lang_finalize_version_expr_head): Don't free.  Delete FIXME.
	(lang_register_vers_node): Don't free.
	(lang_add_vers_depend): Use stat_alloc.
	(lang_do_version_exports_section): Likewise.
	(lang_add_unique): Use stat_alloc and stat_strdup.
	(lang_append_dynamic_list): Use stat_alloc.
	* ldlang.h (stat_memdup, stat_strdup): Declare.
	* ldlex.l: Replace xstrdup with stat_strdup throughout.
	Replace xmemdup with stat_memdup too.
	* lexsup.c (parse_args): Don't free export list or dynamic
	list.