xtensa: add separate property sections option

xtensa: add separate property sections option

It is currently not possible to correctly match .xt.prop information
for sections with identical VMA. Allow creation of separate property
sections in the BFD. Add assembler option --separate-prop-tables to
allow creation of separate property sections.

2018-06-04  Volodymyr Arbatov  <arbatov@cadence.com>
bfd/

	* elf32-xtensa.c (elf32xtensa_separate_props): New global
	variable.
	(xtensa_add_names): New function.
	(xtensa_property_section_name): Add new parameter
	separate_sections, use it to choose property section name.
	(xtensa_get_separate_property_section): New function.
	(xtensa_get_property_section): Invoke
	xtensa_get_separate_property_section to get individual property
	section if it exists, common property section otherwise.
	(xtensa_make_property_section): Pass elf32xtensa_separate_props
	to xtensa_property_section_name.

gas/
	* config/tc-xtensa.c (elf32xtensa_separate_props): New
	declaration.
	(option_separate_props, option_no_separate_props): New
	enumeration constants.
	(md_longopts): Add separate-prop-tables option.
	(md_parse_option): Add cases for option_separate_props and
	option_no_separate_props.
	(md_show_usage): Add help for [no-]separate-prop-tables options.