Update the flycheck configuration for gcc and cppcheck

.dir-locals.el

@@ -61,6 +61,7 @@
 
    (eval setq flycheck-clang-include-path include-directories)
    (eval setq flycheck-cppcheck-include-path include-directories)
+   (eval setq flycheck-gcc-include-path include-directories)
    (eval setq flycheck-clang-args
 	 (list
 	  "-include"
@@ -68,5 +69,20 @@
 	   (concat directory-of-current-dir-locals-file "config.h"))
 	  )
 	 )
+   (eval setq flycheck-gcc-args
+	 (list
+	  "-include"
+	  (expand-file-name
+	   (concat directory-of-current-dir-locals-file "config.h"))
+	  )
+	 )
+   (eval setq flycheck-cppcheck-args
+	 (list
+	  "--enable=all"
+	  "--suppress=missingIncludeSystem"
+	  (concat "-include=" (expand-file-name
+			       (concat directory-of-current-dir-locals-file "config.h")))
+	  )
+	 )
    )
   ))