[Analysis] Fix warnings

This patch fixes:

  llvm/lib/Analysis/IR2Vec.cpp:76:3: error: default label in switch
  which covers all enumeration values
  [-Werror,-Wcovered-switch-default]

  llvm/lib/Analysis/IR2Vec.cpp:218:12: error: unused variable 'Dim'
  [-Werror,-Wunused-variable]

Author: kazutakahirata

llvm/lib/Analysis/IR2Vec.cpp

@@ -73,10 +73,8 @@ Expected<std::unique_ptr<Embedder>> Embedder::create(IR2VecKind Mode,
   switch (Mode) {
   case IR2VecKind::Symbolic:
     return std::make_unique<SymbolicEmbedder>(F, Vocabulary, Dimension);
-  default:
-    return make_error<StringError>("Unknown IR2VecKind",
-                                   errc::invalid_argument);
   }
+  return make_error<StringError>("Unknown IR2VecKind", errc::invalid_argument);
 }
 
 void Embedder::addVectors(Embedding &Dst, const Embedding &Src) {
@@ -217,6 +215,7 @@ Error IR2VecVocabAnalysis::readVocabulary() {
 
   unsigned Dim = Vocabulary.begin()->second.size();
   assert(Dim > 0 && "Dimension of vocabulary is zero");
+  (void)Dim;
   assert(std::all_of(Vocabulary.begin(), Vocabulary.end(),
                      [Dim](const std::pair<StringRef, Embedding> &Entry) {
                        return Entry.second.size() == Dim;