Add new tests for Efinix architecture.

Problems/questions:
	- fsm.ys. equiv_opt -assert failed because of unproven cells;
	- latches.ys,tribuf.ys - internal cells present;
	- memory.ys - sat called with -verify and proof did fail.

tests/efinix/add_sub.v

@@ -0,0 +1,13 @@
+module top
+(
+ input [3:0] x,
+ input [3:0] y,
+
+ output [3:0] A,
+ output [3:0] B
+ );
+
+assign A =  x + y;
+assign B =  x - y;
+
+endmodule