dns: make DNSTransactionAlloc static

src/app-layer-dns-common.c

@@ -155,7 +155,7 @@ void DNSSetEvent(DNSState *s, uint8_t e) {
 /** \internal
  *  \brief Allocate a DNS TX
  *  \retval tx or NULL */
-DNSTransaction *DNSTransactionAlloc(const uint16_t tx_id) {
+static DNSTransaction *DNSTransactionAlloc(const uint16_t tx_id) {
     DNSTransaction *tx = SCMalloc(sizeof(DNSTransaction));
     if (unlikely(tx == NULL))
         return NULL;

src/app-layer-dns-common.h

@@ -177,7 +177,6 @@ uint64_t DNSGetTxCnt(void *alstate);
 int DNSGetAlstateProgress(void *tx, uint8_t direction);
 int DNSGetAlstateProgressCompletionStatus(uint8_t direction);
 
-DNSTransaction *DNSTransactionAlloc(const uint16_t tx_id);
 void DNSStateTransactionFree(void *state, uint64_t tx_id);
 DNSTransaction *DNSTransactionFindByTxId(const DNSState *dns_state, const uint16_t tx_id);