Remove dwarf_decode_lines argumewant_line_info

Remove dwarf_decode_lines argumewant_line_info

Hi,
dwarf_decode_lines is called in two functions,
dwarf2_build_include_psymtabs and handle_DW_AT_stmt_list, in which, 1
is passed to argument 'want_line_info' and 'want_line_info' is a
conditional variable in dwarf_decode_lines.  We can simplify it by
removing 'want_line_info' and propagating the constant 1 into
dwarf_decode_lines.  This is what this patch does.  This patch also
remove one line comment about WANT_LINE_INFO in
handle_DW_AT_stmt_list, as handle_DW_AT_stmt_list doesn't have such
argument.

gdb:

2014-08-28  Yao Qi  <yao@codesourcery.com>

	* dwarf2read.c (dwarf_decode_lines): Update declaration.
	(handle_DW_AT_stmt_list): Remove comment about WANT_LINE_INFO.
	(dwarf_decode_lines): Remove argument
	want_line_info.  Remove condition check on want_line_info.
	Callers update.