ModuleImpls requires pointer identical netlist for Modules

[clavin-xlnx]

In

RapidWright/src/com/xilinx/rapidwright/design/ModuleImpls.java

Lines 64 to 70 in 6df961a

	private void checkSameNetlist() {
	for (Module mod : this) {
	if (mod.getNetlist() != getNetlist()) {
	throw new RuntimeException("In the ModuleImpls "+mod.getName()+", the netlists are not pointer-equal");
	}
	}
	}

Any module with the same name will attempt to combine their implementations. This is not a problem except that most often, multiple implementations will come from multiple DCPs and thus will have distinct copies of their netlist---even if they are identical---in memory. Thus, the check cited above will always fail unless the user is aware of manually ensuring the netlist objects are the same. The goal of this issue is to resolve this discrepancy by finding a low friction path for the user to accomplish this, or to provide a more robust (yet efficient) way of checking that two netlists are equivalent.