Fix build breakage from llvm r351317

The two-argument version of  llvm::sys::fs::make_absolute no longer
returns an error code.

llvm-svn: 351319
diff --git a/clang-tools-extra/clangd/tool/ClangdMain.cpp b/clang-tools-extra/clangd/tool/ClangdMain.cpp
index c5b3c98..34e81d3 100644
--- a/clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ b/clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -223,9 +223,7 @@
     Body = Body.ltrim('/');
     llvm::SmallVector<char, 16> Path(Body.begin(), Body.end());
     path::native(Path);
-    auto Err = fs::make_absolute(TestScheme::TestDir, Path);
-    if (Err)
-      llvm_unreachable("Failed to make absolute path in test scheme.");
+    fs::make_absolute(TestScheme::TestDir, Path);
     return std::string(Path.begin(), Path.end());
   }