PR gold/18048: Fix INCLUDE directive support for gold

PR gold/18048: Fix INCLUDE directive support for gold

This patch fixes INCLUDE directives in script files, so that when
an INCLUDE appears inside a sections block, section commands block,
or memory def block, the contents are parsed in the appropriate
context.

gold/
	PR gold/18048
	* script-c.h (script_include_directive): Add first_token parameter.
	* script.cc (script_include_directive): Add first_token parameter, and
	pass it to read_script_file.
	* yyscript.y (PARSING_SECTIONS_BLOCK, PARSING_SECTION_CMDS)
	(PARSING_MEMORY_DEF): New tokens.
	(top): Add new productions for INCLUDE files.
	(file_cmd): Replace file_or_sections_cmd with copy of its productions.
	Pass PARSING_LINKER_SCRIPT to script_include_directive.
	(section_block_cmd): Likewise; pass PARSING_SECTIONS_BLOCK.
	(section_cmd): Pass PARSING_SECTION_CMDS.
	(file_or_sections_cmd): Remove.
	(memory_def): Pass PARSING_MEMORY_DEF.
	* testsuite/Makefile.am (memory_test_2): New test.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/memory_test_inc.t: New script file.
	* testsuite/memory_test_inc_1.t.src: New script file.
	* testsuite/memory_test_inc_2.t.src: New script file.
	* testsuite/memory_test_inc_3.t.src: New script file.