[ImportResolution] Don't deduplicate scoped imports

This fixes a few tests that were failing because scoped imports were
counted as having imported the module already, leading to later imports
of the same module being skipped. Since the scoped imports don't import
the full module, this would result in syntactically imported symbols not
being found by the compiler.

Author: hnrklssn

lib/Sema/ImportResolution.cpp

@@ -385,11 +385,18 @@ void ImportResolver::bindImport(UnboundImport &&I) {
 
   I.validateOptions(topLevelModule, SF);
 
-  if (!M->isNonSwiftModule() || topLevelModule != M ||
-      seenClangTLMs.insert(M).second) {
+  auto alreadyImportedTLM = [ID,this](const ModuleDecl *MD) {
+    assert(!MD->findUnderlyingClangModule()->isSubModule());
+    // Scoped imports don't import all symbols from the module, so a scoped
+    // import does not count the module as imported
+    if (ID && isScopedImportKind(ID.get()->getImportKind()))
+      return false;
+    return !seenClangTLMs.insert(MD).second;
+  };
+  if (!M->isNonSwiftModule() || topLevelModule != M || !alreadyImportedTLM(M)) {
     addImport(I, M);
     if (topLevelModule && topLevelModule != M &&
-        seenClangTLMs.insert(topLevelModule.get()).second) {
+        !alreadyImportedTLM(topLevelModule.get())) {
       // If we have distinct submodule and top-level module, add both.
       // Importing the submodule ensures that it gets loaded, but the decls
       // are imported to the TLM, so import that for visibility.