Implement -Wmisleading-indentation

gcc/ChangeLog:
	* doc/invoke.texi (Warning Options): Add -Wmisleading-indentation.
	(-Wmisleading-indentation): New option.
	* Makefile.in (C_COMMON_OBJS): Add c-family/c-indentation.o.

gcc/c-family/ChangeLog:
	* c-common.h (warn_for_misleading_indentation): New prototype.
	* c-indentation.c: New file.
	* c.opt (Wmisleading-indentation): New option.

gcc/c/ChangeLog:
	* c-parser.c (c_parser_if_body): Add param "if_loc", use it
	to add a call to warn_for_misleading_indentation.
	(c_parser_else_body): Likewise, adding param "else_loc".
	(c_parser_if_statement): Check for misleading indentation.
	(c_parser_while_statement): Likewise.
	(c_parser_for_statement): Likewise.

gcc/cp/ChangeLog:
	* parser.c (cp_parser_selection_statement): Add location and
	guard_kind arguments to calls to
	cp_parser_implicitly_scoped_statement.
	(cp_parser_iteration_statement): Likewise for calls to
	cp_parser_already_scoped_statement.
	(cp_parser_implicitly_scoped_statement): Add "guard_loc" and
	"guard_kind" params; use them to warn for misleading
	indentation.
	(cp_parser_already_scoped_statement): Likewise.

gcc/testsuite/ChangeLog:
	* c-c++-common/Wmisleading-indentation.c: New testcase.
	* c-c++-common/Wmisleading-indentation-2.c: New testcase.
	* c-c++-common/Wmisleading-indentation-2.md: New file.

libcpp/ChangeLog:
	* directives.c (do_line): Set seen_line_directive on line_table.
	(do_linemarker): Likewise.
	* include/line-map.h (struct line_maps): Add new field
	"seen_line_directive".

From-SVN: r223098