Use effective target in Networking TS tests

Use effective target in Networking TS tests

	* testsuite/experimental/net/headers.cc: Remove dg-options.
	* testsuite/experimental/net/buffer/arithmetic.cc: Replace dg-options
	with dg-do using effective target.
	* testsuite/experimental/net/buffer/const.cc: Likewise.
	* testsuite/experimental/net/buffer/creation.cc: Likewise.
	* testsuite/experimental/net/buffer/mutable.cc: Likewise.
	* testsuite/experimental/net/buffer/size.cc: Likewise.
	* testsuite/experimental/net/buffer/traits.cc: Likewise.
	* testsuite/experimental/net/execution_context/use_service.cc:
	Likewise.
	* testsuite/experimental/net/internet/address/v4/comparisons.cc:
	Likewise.
	* testsuite/experimental/net/internet/address/v4/cons.cc: Likewise.
	* testsuite/experimental/net/internet/address/v4/creation.cc:
	Likewise.
	* testsuite/experimental/net/internet/address/v4/members.cc: Likewise.
	* testsuite/experimental/net/internet/resolver/base.cc: Likewise.
	* testsuite/experimental/net/internet/resolver/ops/lookup.cc:
	Likewise.
	* testsuite/experimental/net/internet/resolver/ops/reverse.cc:
	Likewise.
	* testsuite/experimental/net/timer/waitable/cons.cc: Likewise.
	* testsuite/experimental/net/timer/waitable/dest.cc: Likewise.
	* testsuite/experimental/net/timer/waitable/ops.cc: Likewise.

From-SVN: r265200