Do not return FALSE if sem_wait() fails with EAGAIN

sflphone-client-gnome/src/video/video_preview.c

@@ -360,13 +360,13 @@ readFrameFromShm(VideoPreviewPrivate *priv)
     if (sem_set_id == -1)
         return FALSE;
 
-    if (sem_wait(sem_set_id) == -1) {
+    while (sem_wait(sem_set_id) == -1) {
       if (errno != EAGAIN) {
           g_print("Could not read from shared memory!\n");
           perror("shm: ");
-      }
           return FALSE;
       }
+    }
 
     if (priv->using_clutter) {
         if (strcmp(priv->format, "rgb24")) {