Include the header file to validate function prototype.

src/eap_common/eap_peap_common.c

@@ -16,6 +16,7 @@
 
 #include "common.h"
 #include "sha1.h"
+#include "eap_peap_common.h"
 
 void peap_prfplus(int version, const u8 *key, size_t key_len,
 		  const char *label, const u8 *seed, size_t seed_len,