CppTools: Remove test file after test

In test_includeGroups_detectIncludeGroupsByIncludeType the test file was
not removed and thus subsequent and isolated executions of this test
failed.

Change-Id: I5eeb4f004f5b146ac794ca913b4092629131fca3
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/includeutils.cpp

@@ -509,10 +509,12 @@ using CppTools::Internal::CppToolsPlugin;
 static QList<Include> includesForSource(const QByteArray &source)
 {
     const QString fileName = TestIncludePaths::testFilePath();
-    CppTools::Tests::TestCase::writeFile(fileName, source);
+
+    FileWriterAndRemover scopedFile(fileName, source);
+    if (!scopedFile.writtenSuccessfully())
+        return QList<Include>();
 
     using namespace CppTools::Internal;
-
     CppModelManager *cmm = CppModelManager::instance();
     cmm->GC();
     CppSourceProcessor sourceProcessor((QPointer<CppModelManager>(cmm)));