[llvm] [Xtensa] Implement Xtensa Region Protection Option and several other small Options. (PR #137135)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,17 @@
+# RUN: llvm-mc %s -triple=xtensa -show-encoding --mattr=+dcache \
+# RUN:     | FileCheck -check-prefixes=CHECK,CHECK-INST %s
+
+.align	4
----------------
arsenm wrote:

Do these need mirrored disassembler tests? 

https://github.com/llvm/llvm-project/pull/137135