Fix some test failures

Author: MitalAshok

clang-tools-extra/clangd/unittests/ASTTests.cpp

@@ -80,7 +80,7 @@ TEST(GetDeducedType, KwAutoKwDecltypeExpansion) {
               namespace std
               {
                 template<class _E>
-                class [[initializer_list]] {};
+                class [[initializer_list]] { const _E *a, *b; };
               }
 
               ^auto i = {1,2};

clang-tools-extra/clangd/unittests/XRefsTests.cpp

@@ -771,7 +771,7 @@ TEST(LocateSymbol, All) {
         namespace std
         {
           template<class _E>
-          class [[initializer_list]] {};
+          class [[initializer_list]] { const _E *a, *b; };
         }
 
         ^auto i = {1,2};

clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp

@@ -534,7 +534,7 @@ TEST(WalkAST, Enums) {
 TEST(WalkAST, InitializerList) {
   testWalk(R"cpp(
        namespace std {
-        template <typename T> struct $implicit^initializer_list {};
+        template <typename T> struct $implicit^initializer_list { const T *a, *b; };
        })cpp",
            R"cpp(
        const char* s = "";

clang-tools-extra/test/clang-tidy/checkers/performance/inefficient-vector-operation.cpp

@@ -5,7 +5,8 @@
 
 namespace std {
 
-typedef decltype(sizeof 0) size_t;
+// FIXME: This doesn't work if size_t is not a signed type
+typedef int size_t;
 
 template<class E> class initializer_list {
 public:
@@ -15,8 +16,7 @@ template<class E> class initializer_list {
   using size_type = size_t;
   using iterator = const E*;
   using const_iterator = const E*;
-  iterator ptr;
-  size_type sz;
+  iterator first, last;
   initializer_list();
   size_t size() const; // number of elements
   const E* begin() const; // first element