vtr arch.xml file does not adapt to at least some non-default COFFE settings

[vaughnbetz]

The vtr arch.xml file that COFFE can output does not adapt in some non-delay/non-area ways to the input. The number of inputs and the number of BLEs in particular do not affect the generated arch.xml (beyond affecting the area and delay, which are correct). The attached file shows a case with a CLB of eight 4-LUTs and 18 inputs, but you can see the clb in the architecture xml file has 10 LUTs and 32 inputs. The area and delay values match the COFFE log file, which shows it did size the correct clb; the arch.xml writing is just too hard-coded.
coffe_input_flut08-4.txtcoffe_log_8_fracturable4LUT.log
vtr_arch_flut08-4-xml.txt

This should be fixed -- the vtr.arch file should reflect all the parameters sent into COFFE. If that is too hard in some cases, we should at least print a warning and a banner saying where to fix up the vtr.arch file.