Fixed dead assignments.

Found by Clang Static Analyzer.

src/nxt_buf.c

@@ -201,7 +201,6 @@ nxt_buf_completion(nxt_task_t *task, void *obj, void *data)
     nxt_buf_t  *b, *next, *parent;
 
     b = obj;
-    parent = data;
 
     nxt_debug(task, "buf completion: %p %p", b, b->mem.start);
 
@@ -275,7 +274,6 @@ nxt_buf_ts_completion(nxt_task_t *task, void *obj, void *data)
     nxt_buf_t  *b, *next, *parent;
 
     b = obj;
-    parent = data;
 
     if (nxt_buf_ts_handle(task, obj, data)) {
         return;

src/nxt_event_engine.c

@@ -720,11 +720,10 @@ nxt_event_engine_buf_mem_free(nxt_event_engine_t *engine, nxt_buf_t *b)
 void
 nxt_event_engine_buf_mem_completion(nxt_task_t *task, void *obj, void *data)
 {
-    nxt_event_engine_t  *engine;
     nxt_buf_t           *b, *next, *parent;
+    nxt_event_engine_t  *engine;
 
     b = obj;
-    parent = data;
 
     nxt_debug(task, "buf completion: %p %p", b, b->mem.start);
 

src/nxt_h1proto.c

@@ -955,7 +955,6 @@ nxt_h1p_request_body_read(nxt_task_t *task, nxt_http_request_t *r)
         } else {
             size = nxt_min(body_buffer_size, size);
             b->mem.free = nxt_cpymem(b->mem.free, in->mem.pos, size);
-            body_buffer_size -= size;
         }
 
         in->mem.pos += size;

src/nxt_http_chunk_parse.c

@@ -253,7 +253,6 @@ nxt_http_chunk_buf_completion(nxt_task_t *task, void *obj, void *data)
     nxt_buf_t  *b, *next, *parent;
 
     b = obj;
-    parent = data;
 
     nxt_debug(task, "buf completion: %p %p", b, b->mem.start);
 

src/nxt_isolation.c

@@ -126,10 +126,10 @@ nxt_isolation_main_prefork(nxt_task_t *task, nxt_process_t *process,
             return ret;
         }
 
-        has_mnt = 0;
-
 #if (NXT_HAVE_CLONE_NEWNS)
         has_mnt = nxt_is_clone_flag_set(process->isolation.clone.flags, NEWNS);
+#else
+        has_mnt = 0;
 #endif
 
         if (process->user_cred->uid == 0 && !has_mnt) {

src/nxt_main_process.c

@@ -347,8 +347,6 @@ nxt_port_main_start_process_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     nxt_process_init_t     *init;
     nxt_common_app_conf_t  *app_conf;
 
-    ret = NXT_ERROR;
-
     rt = task->thread->runtime;
 
     process = nxt_main_process_new(task, rt);