Add support for disabling automatic generation of .eh_frame_hdr sections in ELF based linkers.

	PR ld/20537
	* emultempl/elf32.em: More OPTION_xxx values into an enum.  Add
	OPTION_NO_EH_FRAME_HDR.
	(_add_options): Add support for --no-eh-frame-hdr.
	* ld.texinfo: Document new option.
	* lexsup.c (elf_shlib_list_options): List new option.
	* NEWS: Mention the new option.