chore: Force C+ mode for headers

Signed-off-by: Alexander Kurbatov <Alexander.Kurbatov@acronis.com>

Author: Alexander Kurbatov

.dir-locals.el

@@ -3,6 +3,7 @@
 
 ((nil
   (eval . (let ((root (projectile-project-root)))
+            (add-to-list 'auto-mode-alist '("\\.h\\'" . c++-mode))
             (setq-local flycheck-cppcheck-standards "c++14")
             (setq-local flycheck-clang-language-standard "c++14")
             (setq-local flycheck-clang-include-path