[llvm] [TableGen] Print a warning when a Processor contains duplicate Features / TuneFeatures (PR #137864)

[Rahul Joshi via llvm-commits]

jurahul wrote:

I also see:

[2704/5914] Building CSKYGenSubtargetInfo.inc...
warning: Processor ck807e contains duplicate feature 'edsp'
warning: Processor ck807e contains duplicate feature 'dsp1e2'
warning: Processor ck807e contains duplicate feature 'dspe60'
warning: Processor ck807ef contains duplicate feature 'edsp'
warning: Processor ck807ef contains duplicate feature 'dsp1e2'
warning: Processor ck807ef contains duplicate feature 'dspe60'


https://github.com/llvm/llvm-project/pull/137864