Fix: avoid pthread_mutex_lock abort.

This commit is workaround. This issue realy occures with the following log.
lte-softmodem: ../nptl/pthread_mutex_lock.c:81: _pthread_mutex_lock: Assertion `mutex->_data.__owner == 0' failed.

openair2/LAYER2/MAC/eNB_scheduler_dlsch.c

@@ -1011,7 +1011,9 @@ schedule_ue_spec(module_id_t module_idP,
                                              );
 
             if((rrc_release_info.num_UEs > 0) && (rlc_am_mui.rrc_mui_num > 0)) {
-              pthread_mutex_lock(&rrc_release_freelist);
+              while(pthread_mutex_trylock(&rrc_release_freelist)){
+                /* spin... */
+              }
               uint16_t release_total = 0;
 
               for (release_num = 0, release_ctrl = &rrc_release_info.RRC_release_ctrl[0];

openair2/LAYER2/MAC/eNB_scheduler_fairRR.c

@@ -1293,7 +1293,9 @@ schedule_ue_spec_fairRR(module_id_t module_idP,
                                              );
 
             if((rrc_release_info.num_UEs > 0) && (rlc_am_mui.rrc_mui_num > 0)){
-              pthread_mutex_lock(&rrc_release_freelist);
+              while(pthread_mutex_trylock(&rrc_release_freelist)) {
+                /* spin... */
+              }
               uint16_t release_total = 0;
 
               for(uint16_t release_num = 0; release_num < NUMBER_OF_UE_MAX; release_num++) {

openair2/LAYER2/MAC/eNB_scheduler_primitives.c

@@ -2320,7 +2320,9 @@ rrc_mac_remove_ue(module_id_t mod_idP,
   }
 
   if(rrc_release_info.num_UEs > 0){
-  pthread_mutex_lock(&rrc_release_freelist);
+    while(pthread_mutex_trylock(&rrc_release_freelist)) {
+      /* spin... */
+    }
     uint16_t release_total = 0;
 
     for (uint16_t release_num = 0; release_num < NUMBER_OF_UE_MAX; release_num++) {

openair2/RRC/LTE/rrc_eNB.c

@@ -2236,8 +2236,9 @@ rrc_eNB_generate_RRCConnectionRelease(
     ue_context_pP->ue_context.rnti,
     rrc_eNB_mui,
     size);
-  pthread_mutex_lock(&rrc_release_freelist);
-
+  while (pthread_mutex_trylock(&rrc_release_freelist)) {
+    /* spin... */
+  }
   for (uint16_t release_num = 0; release_num < NUMBER_OF_UE_MAX; release_num++) {
     if (rrc_release_info.RRC_release_ctrl[release_num].flag == 0) {
       if (ue_context_pP->ue_context.ue_release_timer_s1 > 0) {