testsuite: assorted targets: add missing braces to dg-* directives

testsuite: assorted targets: add missing braces to dg-* directives

These get ignored otherwise.

gcc/testsuite/ChangeLog:

	* gcc.target/arc/taux-1.c: Add missing brace.
	* gcc.target/arc/taux-2.c: Ditto.
	* gcc.target/i386/addr-space-1.c: Ditto.
	* gcc.target/ia64/mfused-madd-vect.c: Ditto.
	* gcc.target/ia64/mfused-madd.c: Ditto.
	* gcc.target/ia64/mno-fused-madd-vect.c: Ditto.
	* gcc.target/ia64/mno-fused-madd.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls-vlmax/merge-4.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/merge-4.c: Ditto.
	* gcc.target/s390/target-attribute/tattr-1.c: Ditto.
	* gcc.target/s390/target-attribute/tattr-2.c: Ditto.