update tools/build-xilinx.rb

[hiyuh]

Xilinx looks having no passion to support ISE anymore. this issue proposes to update tools/build-xilinx.rb by

• renaming to tools/build-xlinx-ise.rb,
• and adding new tools/build-xilinx-vivado.rb.

NOTE: due to still-available their old devices such as Spartan-3AN, Virtex-4, Virtex-5, Spartan-6 and Virtex-6 are only supported by ISE, so some users can not migrate to Vivado. such users tend to unable to use new devices such as 7-Series, UltraScale and UltraScale+, mainly b/c of its price is simply high. nowadays, Xilinx announces Spartan-7 and releases Vivado HLx Edition. it sounds for no money users.

P.S. i'm not one of above ISE stickers nor no money users. but i usually use Vivado in these days. so keeping ISE support looks not so promising to me.

[nickg]

I agree doing the above rename is a good idea. I don't have Vivado installed at the moment so if someone else could provide the script that would be great.

FWIW we still use Spartan6 at my day job and I know of a couple of other companies that do too.

[hiyuh]

as @mitchsm does renaming/adding appropriate scripts and @nickg merged them. so it's enough to achieve the original goals to a respectable degree. now closing...