@Override
	public int getReturnAddressOffset() {
		synchronized (function) {
			return returnStart;
		}
	}
Get the stack variable containing offset.  This may fall in
the middle of a defined variable.

@param offset offset of on stack to get variable.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/oldfunction/OldStackFrameDB.java