Fixed #321, support for reduce ops in share command

[canaknesil]

The share command aborts if the cell type is a reduce operation. This fix prevents the abort by supporting $reduce_and/or/xor/xnor/bool.

Added the following test that would fail before the fix:

read_verilog <<EOF
module top(a, b, s, y);
	input wire [7:0] a;
	input wire [7:0] b;
	input wire s;
	output wire y;
	assign y = s ? |a : |b;
endmodule
EOF

share -force

[widlarizer]

The FSM tests, that do use share, fail but only on macOS. Strange...

Tagging in a comment so we get a link here on github: this fixes #321

[widlarizer]

The reason it only failed on macos is because the seed is by default random and each runner ran FSM tests with a different seed. ./run-test.sh -S 358331205987550812 in tests/fsm fails in case 15 on this commit, but not on its parent commit

[widlarizer]

I tried bugpoint after commenting out the read_verilog statement from the .ys file like so:

./yosys -p "read_verilog tests/fsm/temp/uut_00015.v; proc; bugpoint -script tests/fsm/temp/uut_00015.ys -yosys ./yosys -grep proof; dump"

However, that reduces it to a test case that also fails on the main branch. I don't know about a way to configure the bugpoint command for a case where we want it to preserve the invariant "test case fails on this yosys binary but passes on that one". Maybe verismith could do this. I don't think I'll continue working on this unless specific user/company needs make it relevant