Fix qbs build of clang format product

Not depending on CppEditor caused linker errors
regarding the cpp highlighter class.

Change-Id: Ib127cbe8e7d8eaa9e7d222dea88585164e49cdd2
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangformat/clangformat.qbs

@@ -5,6 +5,7 @@ QtcPlugin {
 
     Depends { name: "Core" }
     Depends { name: "TextEditor" }
+    Depends { name: "CppEditor" }
     Depends { name: "CppTools" }
     Depends { name: "ProjectExplorer" }
     Depends { name: "Utils" }