Fix clang-6.0 build error and warnings

Error:
 -variable length array folded to constant array as an extension

Warnings:
 -null passed to a callee that requires a non-null
 -equality comparison with extraneous parentheses

Author: Arto Kinnunen

source/6LoWPAN/Thread/thread_extension_bbr.c

@@ -1000,7 +1000,7 @@ static int thread_extension_bbr_dua_cb(int8_t service_id, uint8_t source_address
 typedef struct {
     uint8_t addr[16];
 } multicast_addr_t;
-static multicast_addr_t multicast_store[MULTICAST_ADDRESS_STORE_AMOUNT] = {0};
+static multicast_addr_t multicast_store[MULTICAST_ADDRESS_STORE_AMOUNT] = {{0}};
 
 static void thread_border_router_multicast_store_add(thread_pbbr_t *this, uint8_t *destination_addr_ptr)
 {

source/DHCPv6_client/dhcpv6_client_api.h

@@ -100,7 +100,7 @@ void dhcp_client_global_address_delete(int8_t interface, uint8_t *dhcp_addr, uin
 
 void dhcp_relay_agent_enable(int8_t interface, uint8_t border_router_address[static 16]);
 
-int dhcp_client_server_address_update(int8_t interface, uint8_t prefix[static 16], uint8_t server_address[static 16]);
+int dhcp_client_server_address_update(int8_t interface, uint8_t *prefix, uint8_t server_address[static 16]);
 
 
 

source/DHCPv6_client/dhcpv6_client_service.c

@@ -302,7 +302,7 @@ int dhcp_client_get_global_address(int8_t interface, uint8_t dhcp_addr[static 16
     return 0;
 }
 
-int dhcp_client_server_address_update(int8_t interface, uint8_t prefix[static 16], uint8_t server_address[static 16])
+int dhcp_client_server_address_update(int8_t interface, uint8_t *prefix, uint8_t server_address[static 16])
 {
     dhcpv6_client_server_data_t *srv_data_ptr = NULL;
 

source/Security/protocols/sec_prot_lib.c

@@ -272,7 +272,7 @@ int8_t sec_prot_lib_pmkid_calc(const uint8_t *pmk, const uint8_t *auth_eui64, co
     const uint8_t pmk_string_val[] = {"PMK Name"};
     const uint8_t pmk_string_val_len = sizeof(pmk_string_val) - 1;
 
-    const uint8_t data_len = pmk_string_val_len + EUI64_LEN + EUI64_LEN;
+    uint8_t data_len = pmk_string_val_len + EUI64_LEN + EUI64_LEN;
     uint8_t data[data_len];
     uint8_t *ptr = data;
     memcpy(ptr, pmk_string_val, pmk_string_val_len);
@@ -294,7 +294,7 @@ int8_t sec_prot_lib_ptkid_calc(const uint8_t *ptk, const uint8_t *auth_eui64, co
     const uint8_t ptk_string_val[] = {"PTK Name"};
     const uint8_t ptk_string_val_len = sizeof(ptk_string_val) - 1;
 
-    const uint8_t data_len = ptk_string_val_len + EUI64_LEN + EUI64_LEN;
+    uint8_t data_len = ptk_string_val_len + EUI64_LEN + EUI64_LEN;
     uint8_t data[data_len];
     uint8_t *ptr = data;
     memcpy(ptr, ptk_string_val, ptk_string_val_len);

source/libDHCPv6/libDHCPv6.c

@@ -208,7 +208,7 @@ dhcpv6_client_server_data_t *libdhcpv6_nonTemporal_entry_get_by_transactionId(ui
 dhcpv6_client_server_data_t *libdhcpv6_nonTemporal_entry_get_by_prefix(int8_t interfaceId, uint8_t *prefix)
 {
     ns_list_foreach(dhcpv6_client_server_data_t, cur, &dhcpv6_client_nonTemporal_list) {
-        if ((cur->interfaceId == interfaceId)) {
+        if (cur->interfaceId == interfaceId) {
             if (memcmp(cur->iaNontemporalAddress.addressPrefix, prefix, 8) == 0) {
                 return cur;
             }

test/nanostack/unittest/stub/dhcpv6_client_stub.c

@@ -89,7 +89,7 @@ void dhcp_client_configure(int8_t interface, bool renew_uses_solicit, bool one_c
 
 }
 
-int dhcp_client_server_address_update(int8_t interface, uint8_t prefix[static 16], uint8_t server_address[static 16])
+int dhcp_client_server_address_update(int8_t interface, uint8_t *prefix, uint8_t server_address[static 16])
 {
     return 0;
 }