Do not use "extern" in header files

include/legic_prng.h

@@ -10,10 +10,10 @@
 #define __LEGIC_PRNG_H
 
 #include <stdint.h>
-extern void legic_prng_init(uint8_t init);
-extern void legic_prng_forward(int count);
-extern int  legic_prng_count();
-extern uint8_t legic_prng_get_bit();
+void legic_prng_init(uint8_t init);
+void legic_prng_forward(int count);
+int  legic_prng_count();
+uint8_t legic_prng_get_bit();
 
 #endif