re PR c/19606 (wrong code for arith.expr: (((unsigned int)(signed int) a ) / 2LL) with signed char a=-4)

gcc/
	PR c/19606.
	* c-typeck.c (build_binary_op): Perform implicit casts of
	operands before shortening them.

gcc/testsuite/
	PR c/19606.
	* gcc.c-torture/execute/pr19606.c: New.

From-SVN: r110321