[clang-repl] Do not assert if we have weak references left.

[v.g.vassilev]

Summary

Non-incremental Clang can also exit with the WeakRefReferences not empty upon such example. This patch makes clang-repl consistent to what Clang does.

[junaire]

This patch fixes issues that have not been found in the past. This unblocks D141215 and D146809. Since it's only relevant to the clang-repl, I believe this is safe to just land it. (I added these assertions in https://reviews.llvm.org/rGcd64a427efa0baaf1bb7ae624d4301908afc07f7 ) However, it will be nice if other reviewers, maybe @rjmccall could take a look at this as well.

[v.g.vassilev]

Provide a better test case.

clang/lib/CodeGen/CodeGenModule.cpp

void CodeGenModule::moveLazyEmissionStates(CodeGenModule *NewBuilder) {
   NewBuilder->DeferredVTables = std::move(DeferredVTables);
 
   assert(NewBuilder->MangledDeclNames.empty() &&
          "Newly created module should not have mangled decl names");
   assert(NewBuilder->Manglings.empty() &&
          "Newly created module should not have manglings");
   NewBuilder->Manglings = std::move(Manglings);
 
-  assert(WeakRefReferences.empty() && "Not all WeakRefRefs have been applied");
   NewBuilder->WeakRefReferences = std::move(WeakRefReferences);
 
   NewBuilder->TBAA = std::move(TBAA);
 
   assert(NewBuilder->EmittedDeferredDecls.empty() &&
          "Still have (unmerged) EmittedDeferredDecls deferred decls");
 
   NewBuilder->EmittedDeferredDecls = std::move(EmittedDeferredDecls);
 
   NewBuilder->ABI->MangleCtx = std::move(ABI->MangleCtx);
 }

clang/test/Interpreter/execute-weak.cpp

 // RUN: clang-repl "int x = 10;" "int y=7; err;" "int y = 10;"
 // RUN: clang-repl "int i = 10;" 'extern "C" int printf(const char*,...);' \
 // RUN:            'auto r1 = printf("i = %d\n", i);' | FileCheck --check-prefix=CHECK-DRIVER %s
 // CHECK-DRIVER: i = 10
+//
 // UNSUPPORTED: system-aix, system-windows
 // RUN: cat %s | clang-repl | FileCheck %s
+
 extern "C" int printf(const char *, ...);
 int __attribute__((weak)) bar() { return 42; }
 auto r4 = printf("bar() = %d\n", bar());
 // CHECK: bar() = 42
 
+int a = 12;
+static __typeof(a) b __attribute__((__weakref__("a")));
+int c = b;
+
 %quit