Fix up vla, vm and [*] sematics.

	PR c/18740
	PR c/7948
	PR c/25802
	* c-tree.h (struct c_arg_info): Add had_vla_unspec.
	(c_vla_unspec_p): Add.
	(c_vla_type_p): Add.
	* c-decl.c (struct c_scope): Add had_vla_unspec.
	(build_array_declarator): Add support for [*].
	(grokdeclarator): Likewise.
	(grokparms): Likewise.
	(get_parm_info): Likewise.
	* c-objc-common.c (c_vla_unspec_p): Likewise.
	* c-objc-common.h (LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P): Likewise.
	* c-parser.c (c_parser_typeof_specifier): Evaluate arguments to
	typeof when argument is a variably modified type not inside sizeof or alignof.
	(c_parser_direct_declarator_inner): Propagate errors.
	(c_parser_sizeof_expression): Add support for [*].
	* c-typeck.c (c_vla_type_p): Add.
	(composite_type): Add support for vla compositing.
	(comptypes_internal): Add support for vla compatibility.
	(c_expr_sizeof_expr): Evaluate vla arguments.
	* tree.c (variably_modified_type_p): Update comment for [*].

testsuite:
	* gcc.dg/c90-arraydecl-1.c: Update for vla, vm [*] fixups.
	* gcc.dg/vla-4.c: Add.
	* gcc.dg/vla-5.c: Add.
	* gcc.dg/vla-6.c: Add.

From-SVN: r113888