[lldb] Silence a GCC warning about missing returns after a fully covered switch. NFC.

GitOrigin-RevId: b7c5683fac3de2f3349d57b9e133ac53204b1148
diff --git a/source/Core/Disassembler.cpp b/source/Core/Disassembler.cpp
index 4c57be4..cc35463 100644
--- a/source/Core/Disassembler.cpp
+++ b/source/Core/Disassembler.cpp
@@ -599,6 +599,7 @@
   case eInstructionControlFlowKindFarJump:
     return "far jump";
   }
+  llvm_unreachable("Fully covered switch above!");
 }
 
 void Instruction::Dump(lldb_private::Stream *s, uint32_t max_opcode_byte_size,