UCS/UCT: Fix issues found by coverity.

* Return value from ucs_memtrack_mmap should be MAP_FAILED and not NULL
* Fix error flow in ucs_init

src/ucs/debug/memtrack.c

@@ -225,13 +225,14 @@ void *ucs_memtrack_mmap(void *addr, size_t length, int prot, int flags,
                         int fd, off_t offset UCS_MEMTRACK_ARG)
 {
     ucs_memtrack_buffer_t *res;
+
     if ((flags & MAP_FIXED) || !(prot & PROT_WRITE)) {
-        return NULL;
+        return MAP_FAILED;
     }
 
     res = mmap(addr, length + (ucs_memtrack_context.enabled ? sizeof(*res) : 0),
                prot, flags, fd, offset);
-    if ((res == NULL) || (!ucs_memtrack_context.enabled)) {
+    if ((res == MAP_FAILED) || (!ucs_memtrack_context.enabled)) {
         return res;
     }
 

src/uct/tl/context.c

@@ -18,18 +18,27 @@ ucs_status_t uct_init(uct_context_h *context_p)
     uct_context_t *context;
 
     context = ucs_malloc(ucs_components_total_size(uct_context_t), "uct context");
+    if (context == NULL) {
+        status = UCS_ERR_NO_MEMORY;
+        goto err;
+    }
 
     context->num_tls  = 0;
     context->tls      = NULL;
     ucs_notifier_chain_init(&context->progress_chain);
 
     status = ucs_components_init_all(uct_context_t, context);
     if (status != UCS_OK) {
-        return status;
+        goto err_free;
     }
 
     *context_p = context;
     return UCS_OK;
+
+err_free:
+    ucs_free(context);
+err:
+    return status;
 }
 
 void uct_cleanup(uct_context_h context)