match: Use tree_expr_nonnegative_p instead of

TYPE_UNSIGNED for MAX (A, B) (==,!=) 0 -> (A|B) (==,!=) 0 [PR125749]

tree_expr_nonnegative_p covers non negative signed type variables,
unlike TYPE_UNSIGNED.

Bootstrapped and tested on x86_64-pc-linux-gnu

	PR tree-optimization/125749

gcc/ChangeLog:

	PR tree-optimization/125749
	* match.pd: Use tree_expr_nonnegative_p for MAX (A, B) (==,!=) 0 ->
	(A|B) (==,!=) 0.

gcc/testsuite/ChangeLog:

	PR tree-optimization/125749
	* gcc.dg/pr125749.c: New test.

Signed-off-by: Kael Franco <kaelfandrew@gmail.com>