arc: Update tumaddsidi4 test.

The test is using -O1 and, the macu instruction is generated by the
combiner and not in the expand step. My previous "arc: Improve code
gen for 64bit add/sub operations." is actually splitting the 64-bit
add in the expand, leading to the impossibility to match the multiply
and accumulate on 64 bit datum by the combiner, hence, the error. This
patch is stepping up the optimization level which will generate the
macu instruction at the expand time.

xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* gcc.target/arc/tumaddsidi4.c: Step-up optimization level.

Signed-off-by: Claudiu Zissulescu <claziss@gmail.com>

gcc/testsuite/ChangeLog

+2020-03-06  Claudiu Zissulescu  <claziss@synopsys.com>
+
+	* gcc.target/arc/tumaddsidi4.c: Step-up optimization level.
+
 2020-03-06  Delia Burduv  <delia.burduv@arm.com>
 
 	* gcc.target/arm/simd/bf16_vldn_1.c: New test.

gcc/testsuite/gcc.target/arc/tumaddsidi4.c

 /* { dg-do compile } */
-/* { dg-options "-mcpu=archs -O1 -mmpy-option=plus_dmpy -w" } */
+/* { dg-options "-mcpu=archs -O2 -mmpy-option=plus_dmpy -w" } */
 
 /* Check how we generate umaddsidi4 patterns.  */
 long a;
@@ -11,4 +11,4 @@ void fn1(void)
   b = d * (long long)c + a;
 }
 
-/* { dg-final { scan-assembler "macu 0,r" } } */
+/* { dg-final { scan-assembler "macu" } } */