* testsuite/experimental/optional/constexpr/observers/1.cc: Remove
	unused header.
	* testsuite/experimental/optional/constexpr/observers/2.cc: Likewise.
	* testsuite/experimental/optional/constexpr/observers/3.cc: Likewise.
	* testsuite/experimental/optional/constexpr/observers/4.cc: Likewise.
	* testsuite/experimental/optional/constexpr/observers/5.cc: Likewise.

From-SVN: r217401