Implement N3928 - Extending static_assert

Implement N3928 - Extending static_assert

cp/

2015-06-24  Edward Smith-Rowland  <3dw4rd@verizon.net>

	Implement N3928 - Extending static_assert
	* parser.c (cp_parser_static_assert): Support static_assert with
	no message string.  Supply an empty string in this case.
	* semantics.c (finish_static_assert): Don't try to print a message if
	the message strnig is empty.

testsuite/

2015-06-24  Edward Smith-Rowland  <3dw4rd@verizon.net>

	Implement N3928 - Extending static_assert
	* g++.dg/cpp0x/static_assert8.C: Adjust.
	* g++.dg/cpp0x/static_assert12.C: New.
	* g++.dg/cpp0x/static_assert13.C: New.
	* g++.dg/cpp1y/static_assert1.C: New.
	* g++.dg/cpp1y/static_assert2.C: New.
	* g++.dg/cpp1z/static_assert-nomsg.C: New.

From-SVN: r224903