wpa_supplicant: fix errors for GCC 8 support

components/wpa_supplicant/port/include/os.h:259:29: error: 'strncpy' output truncated before terminating nul copying 3 bytes from a string of the same length [-Werror=stringop-truncation]
 #define os_strncpy(d, s, n) strncpy((d), (s), (n))
                             ^~~~~~~~~~~~~~~~~~~~~~
components/wpa_supplicant/src/wpa2/eap_peer/eap.c:410:3: note: in expansion of macro 'os_strncpy'
   os_strncpy(sm->blob[0].name, CLIENT_CERT_NAME, BLOB_NAME_LEN);
   ^~~~~~~~~~

components/wpa_supplicant/src/wpa2/eap_peer/eap.c

@@ -407,7 +407,7 @@ int eap_peer_blob_init(struct eap_sm *sm)
 			ret = -2;
 			goto _out;
 		}
-		os_strncpy(sm->blob[0].name, CLIENT_CERT_NAME, BLOB_NAME_LEN);
+		os_strncpy(sm->blob[0].name, CLIENT_CERT_NAME, BLOB_NAME_LEN+1);
 		sm->blob[0].len = g_wpa_client_cert_len;
 		sm->blob[0].data = g_wpa_client_cert;
 	}
@@ -418,7 +418,7 @@ int eap_peer_blob_init(struct eap_sm *sm)
 			ret = -2;
 			goto _out;
 		}
-		os_strncpy(sm->blob[1].name, PRIVATE_KEY_NAME, BLOB_NAME_LEN);
+		os_strncpy(sm->blob[1].name, PRIVATE_KEY_NAME, BLOB_NAME_LEN+1);
 		sm->blob[1].len = g_wpa_private_key_len;
 		sm->blob[1].data = g_wpa_private_key;
 	}
@@ -429,7 +429,7 @@ int eap_peer_blob_init(struct eap_sm *sm)
 			ret = -2;
 			goto _out;
 		}
-		os_strncpy(sm->blob[2].name, CA_CERT_NAME, BLOB_NAME_LEN);
+		os_strncpy(sm->blob[2].name, CA_CERT_NAME, BLOB_NAME_LEN+1);
 		sm->blob[2].len = g_wpa_ca_cert_len;
 		sm->blob[2].data = g_wpa_ca_cert;
 	}