builtin copysign tests: Disable TARGET_SSE_PACKED_SINGLE_INSN_OPTIMAL

Disable TARGET_SSE_PACKED_SINGLE_INSN_OPTIMAL in builtin copysign tests
to avoid

FAIL: gcc.target/i386/builtin-copysign-4.c check-function-bodies foo
FAIL: gcc.target/i386/builtin-copysign-5.c check-function-bodies foo
FAIL: gcc.target/i386/builtin-copysign-6.c check-function-bodies foo
FAIL: gcc.target/i386/builtin-copysign-7.c check-function-bodies foo
FAIL: gcc.target/i386/builtin-copysign-8a.c check-function-bodies foo

due to the generated instruction

	andps	.LC1(%rip), %xmm0

vs the expected instruction

	pand	.LC1(%rip), %xmm0

when TARGET_SSE_PACKED_SINGLE_INSN_OPTIMAL is enabled by default.

	PR testsuite/126923
	* gcc.target/i386/builtin-copysign-4.c (dg-options): Add
	-mtune-ctrl=^sse_packed_single_insn_optimal.
	* gcc.target/i386/builtin-copysign-5.c (dg-options): Likewise.
	* gcc.target/i386/builtin-copysign-6.c (dg-options): Likewise.
	* gcc.target/i386/builtin-copysign-7.c (dg-options): Likewise.
	* gcc.target/i386/builtin-copysign-8a.c (dg-options): Likewise.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>