Handle multiple 'default' in target attribute (PR middle-end/89970).

Handle multiple 'default' in target attribute (PR middle-end/89970).

2019-04-12  Martin Liska  <mliska@suse.cz>

	PR middle-end/89970
	* multiple_target.c (create_dispatcher_calls): Wrap ifunc
	in error message.
	(separate_attrs): Handle multiple 'default's.
	(expand_target_clones): Rework error handling code.
2019-04-12  Martin Liska  <mliska@suse.cz>

	PR middle-end/89970
	* gcc.target/i386/mvc15.c: New test.
	* gcc.target/i386/mvc3.c: Quote target in error pattern.
	* gcc.target/i386/mvc4.c: Remove duplicit 'default'.

From-SVN: r270314