Some subtests were reported as UNSUPPORTED when running under LTO.
That was just because the relevant variables were optimized out.
Mark those variables as used. Now const-volatile reports 192 PASS.

gcc/testsuite/ChangeLog

	* gcc.dg/guality/const-volatile.c (i): Mark as used.
	(ci): Likewise.
	(pci): Likewise.
	(pvi): Likewise.
	(pcvi): Likewise.
	(cip): Likewise.
	(foo): Likewise.
	(cfoo): Likewise.

From-SVN: r215502