Duplicate output sections in scripts

Previously, ld merged duplicate output sections if such existed in
scripts, except for those with a constraint of SPECIAL.  This makes
scripts with duplicate output section statements create duplicate
output sections in the linker output file.

	* ldlang.c (lang_output_section_statement_lookup): Change "create"
	parameter to a tristate, if 2 then always create a new output
	section statement.  Update all callers, with
	lang_enter_output_section_statement using "2".
	(map_input_to_output_sections): Don't ignore SPECIAL constraint
	here.
	* ldlang.h (lang_output_section_statement_type): Update prototype.
	(lang_output_section_find): Update.