MATCH [PR19832]: Optimize some `(a != b) ? a OP b : c`

MATCH [PR19832]: Optimize some `(a != b) ? a OP b : c`

This patch adds the following match patterns to optimize these:
 /* (a != b) ? (a - b) : 0 -> (a - b) */
 /* (a != b) ? (a ^ b) : 0 -> (a ^ b) */
 /* (a != b) ? (a & b) : a -> (a & b) */
 /* (a != b) ? (a | b) : a -> (a | b) */
 /* (a != b) ? min(a,b) : a -> min(a,b) */
 /* (a != b) ? max(a,b) : a -> max(a,b) */
 /* (a != b) ? (a * b) : (a * a) -> (a * b) */
 /* (a != b) ? (a + b) : (a + a) -> (a + b) */
 /* (a != b) ? (a + b) : (2 * a) -> (a + b) */
Note currently only integer types (include vector types)
are handled. Floating point types can be added later on.

OK? Bootstrapped and tested on x86_64-linux-gnu.

The first pattern had still shows up in GCC in cse.c's preferable
function which was the original motivation for this patch.

	PR tree-optimization/19832

gcc/ChangeLog:

	* match.pd: Add pattern to optimize
	`(a != b) ? a OP b : c`.

gcc/testsuite/ChangeLog:

	* g++.dg/opt/vectcond-1.C: New test.
	* gcc.dg/tree-ssa/phi-opt-same-1.c: New test.