* config/obj-coff-seh.c: Rewrite the entire file.

	* config/obj-coff-seh.c: Rewrite the entire file.
	(symtab, symptr, reltab, relcount, relsize): Remove.
	(seh_ctx_root, seh_ctx): Remove.
	(xdata_seg, xdata_subseg, pdata_seg): New.
	(switch_xdata, switch_pdata): New.
	(verify_context, verify_context_and_target, skip_whitespace_and_comma):
	New parsing functions.  Rewrite all parsing functions to use them.
	(obj_coff_seh_32): Fix != arm thinko.
	(obj_coff_seh_handler): For x64, don't accept handler pointer here,
	only flags.
	(obj_coff_seh_handlerdata): New.
	(do_seh_endproc): Split out of ...
	(obj_coff_seh_endproc): ... here.
	(obj_coff_seh_proc): Use it, if needed.
	(seh_x64_make_prologue_element): Use XRESIZEVEC, symbol_temp_new_now.
	(seh_x64_read_reg): Remove mm_regs alternative.  Tidy integer reg
	alternatives.  Don't slurp commas.
	(seh_read_offset): Remove.
	(obj_coff_seh_pushframe): Split out from obj_coff_seh_push.
	(obj_coff_seh_scope): Remove.
	(obj_coff_seh_save): Decide UWOP_SAVE_* vs _FAR immediately.
	(obj_coff_seh_stackalloc): Decide _SMALL vs _LARGE immediately.
	(out_one, out_two, out_four): New.
	(seh_x64_write_prologue_data, seh_x64_size_prologue_data,
	seh_x64_write_function_xdata, write_function_xdata): Rewrite
	from seh_x64_write_xdata, seh_needed_unwind_info, seh_store_elm_data,
	seh_getelm_data_size, seh_getsize_of_unwind_entry,
	seh_make_unwind_entry, seh_getsize_unwind_data, and
	seh_create_unwind_data.
	(seh_arm_write_function_pdata): Rewrite from seh_arm_create_pdata.
	(write_function_pdata): Rewrite from make_function_entry_pdata.
	(seh_write_text_eh_data, make_function_entry_pdata,
	seh_arm_create_pdata, seh_arm_write_pdata, seh_reloc, save_relocs,
	seh_symbol_init, seh_symbol, quick_section, seh_emit_rva,
	seh_emit_long, seh_make_globl, seh_make_section2, seh_make_section,
	seh_make_xlbl_name, make_seh_text_label, seh_fill_pcsyms,
	seh_needed_unwind_info, seh_store_elm_data, seh_getelm_data_size,
	seh_getsize_of_unwind_entry, seh_make_unwind_entry,
	seh_getsize_unwind_data, seh_create_unwind_data,
	seh_make_function_entry_xdata, seh_x64_makescope_elem): Remove.
	* config/obj-coff-seh.h (SEH_CMDS): Remove seh_savemm, seh_scope.
	Add seh_handlerdata.  Adjust function/what arguments for
	seh_savereg, seh_pushframe, seh_stackalloc.
	(struct seh_prologue_element): Adjust members to closer match
	the elements of the UNWIND_CODE structure.
	(struct seh_scope_elem): Remove.
	(struct seh_context): Replace char* members with symbolS or
	expressionS as appropriate.  Sort members by ARM/x64 applicability.
	Remove obsolete stuff wrt direct symbol and reloc manipulation.