[ARC] Update (u)maddsidi patterns.

[ARC] Update (u)maddsidi patterns.

The accumulator registers are freely used by the compiler. However,
there are a number of instructions which are having an intrinsic use
of these registers. Update patterns to inform the compiler which ones.

gcc/
2017-09-19  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.md (maddsidi4, maddsidi4_split): Update pattern.
	(umaddsidi4,umaddsidi4): Likewise.

gcc/testsuite
2017-09-19  Claudiu Zissulescu  <claziss@synopsys.com>

	* gcc.target/arc/tumaddsidi4.c: New test.

From-SVN: r255779