Add semicolon to recent MSVC fix.

llvm-svn: 334093
diff --git a/clang-tools-extra/clangd/Quality.cpp b/clang-tools-extra/clangd/Quality.cpp
index ed3b9b5..a5e0f85 100644
--- a/clang-tools-extra/clangd/Quality.cpp
+++ b/clang-tools-extra/clangd/Quality.cpp
@@ -90,7 +90,7 @@
     case index::SymbolKind::Unknown:
       return SymbolQualitySignals::Unknown;
   }
-  llvm_unreachable("Unknown index::SymbolKind")
+  llvm_unreachable("Unknown index::SymbolKind");
 }
 
 void SymbolQualitySignals::merge(const CodeCompletionResult &SemaCCResult) {