Add missing extern "C" guard in aesni.h

include/polarssl/aesni.h

@@ -37,6 +37,10 @@
 
 #if defined(POLARSSL_HAVE_X86_64)
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * \brief          AES-NI features detection routine
  *
@@ -99,6 +103,10 @@ int aesni_setkey_enc( unsigned char *rk,
                       const unsigned char *key,
                       size_t bits );
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* POLARSSL_HAVE_X86_64 */
 
 #endif /* POLARSSL_AESNI_H */