[llvm] [Xtensa] Add esp32/esp8266 cpus implementation. (PR #152409)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,78 @@
+//==-- XtensaTargetParser - Parser for Xtensa features --*- C++ -*-=//
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MaskRay wrote:

https://llvm.org/docs/CodingStandards.html#file-headers
`//===----------------------------------------------------------------------===//` for new C++ files.

https://github.com/llvm/llvm-project/pull/152409