Improve EVM intruction test

[feliam]

Make tests for all intructions (not just some) https://github.com/trailofbits/manticore/tree/master/tests/EVM
Add symbolic tests where all the input state is symbolic in different ways.

[feliam]

Maybe like this?

manticore/tests/eth_general.py

Lines 367 to 380 in 59a5ff0

	def test_SDIV(self):
	constraints, world, vm = self._make()
	result = vm.SDIV(115792089237316182568066630936765703517573245936339743861833633745570447228928, 200867255532373784442745261542645325315275374222849104412672)
	self.assertEqual(-64, result)
	def test_SDIVS1(self):
	constraints, world, vm = self._make()
	xx = constraints.new_bitvec(256, name="x")
	yy = constraints.new_bitvec(256, name="y")
	constraints.add(xx == 0x20)
	constraints.add(yy == 1)
	result = vm.SDIV(xx, yy)
	self.assertListEqual(solver.get_all_values(constraints, result), [0x20])

[disconnect3d]

Closing this as I believe this is already done with VMTests and will be extended with GeneralStateTests (see #1163).