[fir][NFC] Add two negative tests for needExternalNameMangling

[clementval]

Summary

Add two test for needExternalNameMangling.

• One varibale in a function
• One namelist in a module

This patch is part of the upstreaming effort from fir-dev branch.

flang/unittests/Optimizer/InternalNamesTest.cpp

bool isObjEqual(const NameUniquer::DeconstructedName &actualObj) {
     if ((actualObj.name == name) && (actualObj.modules == modules) &&
         (actualObj.host == host) && (actualObj.kinds == kinds)) {
       return true;
     }
     return false;
   }
 
 private:
-  llvm::SmallVector<std::string, 2> modules;
+  llvm::SmallVector<std::string> modules;
   llvm::Optional<std::string> host;
   std::string name;
-  llvm::SmallVector<std::int64_t, 4> kinds;
+  llvm::SmallVector<std::int64_t> kinds;
 };
 
 void validateDeconstructedName(
     std::pair<NameUniquer::NameKind, NameUniquer::DeconstructedName> &actual,
     NameUniquer::NameKind &expectedNameKind,
     struct DeconstructedName &components) {
   EXPECT_EQ(actual.first, expectedNameKind)
       << "Possible error: NameKind mismatch";

 
 TEST(InternalNamesTest, needExternalNameMangling) {
   ASSERT_FALSE(
       NameUniquer::needExternalNameMangling("_QMmodSs1modSs2modFsubPfun"));
   ASSERT_FALSE(NameUniquer::needExternalNameMangling("omp_num_thread"));
   ASSERT_FALSE(NameUniquer::needExternalNameMangling(""));
   ASSERT_FALSE(NameUniquer::needExternalNameMangling("_QDTmytypeK2K8K18"));
   ASSERT_FALSE(NameUniquer::needExternalNameMangling("exit_"));
+  ASSERT_FALSE(NameUniquer::needExternalNameMangling("_QFfooEx"));
+  ASSERT_FALSE(NameUniquer::needExternalNameMangling("_QFmstartGmpitop"));
   ASSERT_TRUE(NameUniquer::needExternalNameMangling("_QPfoo"));
   ASSERT_TRUE(NameUniquer::needExternalNameMangling("_QPbar"));
   ASSERT_TRUE(NameUniquer::needExternalNameMangling("_QBa"));
 }
 
 TEST(InternalNamesTest, isExternalFacingUniquedName) {
   std::pair result = NameUniquer::deconstruct("_QMmodSs1modSs2modFsubPfun");