Detect C++ language from all C++ file extensions

tests/samples/codefiles/c_and_cxx/non_empty.cxx

@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include <openssl/rand.h>
+
+main()
+{
+    printf("Hello World\n");
+    return 0;
+}

tests/test_languages.py

@@ -69,6 +69,12 @@ class LanguagesTestCase(utils.TestCase):
             entity='c_and_cpp/cpp.h',
         )
 
+    def test_cpp_language_detected_for_header_with_c_and_cxx_files_in_folder(self):
+        self.shared(
+            expected_language='C++',
+            entity='c_and_cxx/cpp.h',
+        )
+
     def test_c_not_detected_for_non_header_with_c_files_in_folder(self):
         self.shared(
             expected_language='Python',