console: add header protection

The header was missing a #ifndef to protect against multiple inclusions.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

src/console.h

@@ -35,6 +35,9 @@
  * of it.
  */
 
+#ifndef KMSCON_CONSOLE_H
+#define KMSCON_CONSOLE_H
+
 #include <inttypes.h>
 #include <stdlib.h>
 #include "font.h"
@@ -79,3 +82,5 @@ void kmscon_console_map(struct kmscon_console *con);
 
 void kmscon_console_write(struct kmscon_console *con, kmscon_symbol_t ch);
 void kmscon_console_newline(struct kmscon_console *con);
+
+#endif /* KMSCON_CONSOLE_H */