[NFC] Use LLVM naming conventions within FileDistance

Reviewed by: sammccall

Differential Revision: https://reviews.llvm.org/D51527

llvm-svn: 341182
diff --git a/clang-tools-extra/clangd/FileDistance.h b/clang-tools-extra/clangd/FileDistance.h
index f07804f..631fddf 100644
--- a/clang-tools-extra/clangd/FileDistance.h
+++ b/clang-tools-extra/clangd/FileDistance.h
@@ -66,7 +66,7 @@
 // This object should be reused, it memoizes intermediate computations.
 class FileDistance {
 public:
-  static constexpr unsigned kUnreachable = std::numeric_limits<unsigned>::max();
+  static constexpr unsigned Unreachable = std::numeric_limits<unsigned>::max();
 
   FileDistance(llvm::StringMap<SourceParams> Sources,
                const FileDistanceOptions &Opts = {});