Disable license regeneration for Tofino backend

[asl]

backend/tofino/LICENSE is regenerated every time during the build. It is very easy to miss updated file when doing e.g. git commit -a and commit a license change therefore.

[Vineet1101]

@asl Taking this issue

[Vineet1101]

@asl I want to know that when should the license file be generated or it should never be generated???

[asl]

Well, my understanding (though I am not a lawyer) is that the license should never be generated. As otherwise any contributor could change the license of Tofino backend, which is definitely something noone should do without explicit approval from the steak-holders :)

[jafingerhut]

I do not know the history behind this license file being generated at build time. @pkotikal @hanw Do you, perhaps?

Since the Tofino code is now released under the Apache-2.0 license, the top level LICENSE file saying that p4c is released under Apache-2.0 should cover it as well.

[Vineet1101]

@asl so I think we should remove the command to generate the license file at build time

[asl]

@asl so I think we should remove the command to generate the license file at build time

That's my point :)