* c-common.c (flag_abi_version): Default to 2.
	* c-cppbuiltin.c (c_cpp_builtins): Define __GXX_ABI_VERSION
	uniformly for versions above 2.
	* doc/invoke.texi: Update documentation for -fabi-version.

	* cp-lang.c (cp_expr_size): Return zero for empty classes.

	* cp-tree.h (warn_if_uknown_interface): Remove unused function.
	* decl2.c (warn_if_unknown_interface): Likewise.

	* g++.dg/abi/macro0.C: New test.
	* g++.dg/abi/macro1.C: Likewise.
	* g++.dg/abi/macro2.C: Likewise.

	* g++.dg/abi/bitfield5.C: Add explicit -fabi-version=1 option.
	* g++.dg/abi/bitfield7.C: Likewise.
	* g++.dg/abi/dtor2.C: Likewise.
	* g++.dg/abi/mangle11.C: Likewise.
	* g++.dg/abi/mangle12.C: Likewise.
	* g++.dg/abi/mangle14.C: Likewise.
	* g++.dg/abi/mangle17.C: Likewise.
	* g++.dg/abi/vbase10.C: Likewise.
	* g++.dg/abi/vbase14.C: Likewise.
	* g++.dg/template/qualttp17.C: Likewise.

From-SVN: r74973