re PR target/83210 (__builtin_mul_overflow() generates suboptimal code when exactly one argument is the constant 2)

	PR target/83210
	* internal-fn.c (expand_mul_overflow): Optimize unsigned
	multiplication by power of 2 constant into two shifts + comparison.

	* gcc.target/i386/pr83210.c: New test.

From-SVN: r255269