Updated Symbol tutorial with Gluon (#12190)
Updated Symbol tutorial with Gluon (#12190)

* Corrections to profiling tutorial

Corrected a race condition with stopping profiling. Added mx.nd.waitall to ensure all operations have completed, including GPU operations that might otherwise be missing.

Also added alternative code for context selection GPU vs CPU, that had error before on machines with nvidia-smi.

* Updated tutorial to include references to Gluon.

tlby/mxnet,zhreshold/mxnet,yajiedesign/mxnet,szha/mxnet,dmlc/mxnet,ptrendx/mxnet,eric-haibin-lin/mxnet,tlby/mxnet,dmlc/mxnet,dmlc/mxnet,zhreshold/mxnet,ptrendx/mxnet,sxjscience/mxnet,szha/mxnet,ptrendx/mxnet,tlby/mxnet,zhreshold/mxnet,sxjscience/mxnet,reminisce/mxnet,mbaijal/incubator-mxnet,dmlc/mxnet,szha/mxnet,ptrendx/mxnet,szha/mxnet,mbaijal/incubator-mxnet,mbaijal/incubator-mxnet,larroy/mxnet,ptrendx/mxnet,larroy/mxnet,ptrendx/mxnet,tlby/mxnet,tlby/mxnet,yajiedesign/mxnet,dmlc/mxnet,yajiedesign/mxnet,szha/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,eric-haibin-lin/mxnet,DickJC123/mxnet,apache/incubator-mxnet,ptrendx/mxnet,ptrendx/mxnet,leezu/mxnet,dmlc/mxnet,szha/mxnet,DickJC123/mxnet,larroy/mxnet,sxjscience/mxnet,szha/mxnet,dmlc/mxnet,leezu/mxnet,ForkedReposBak/mxnet,tlby/mxnet,sxjscience/mxnet,szha/mxnet,zhreshold/mxnet,ForkedReposBak/mxnet,leezu/mxnet,sxjscience/mxnet,ptrendx/mxnet,reminisce/mxnet,eric-haibin-lin/mxnet,eric-haibin-lin/mxnet,yajiedesign/mxnet,szha/mxnet,ForkedReposBak/mxnet,sxjscience/mxnet,leezu/mxnet,apache/incubator-mxnet,ForkedReposBak/mxnet,DickJC123/mxnet,reminisce/mxnet,leezu/mxnet,sxjscience/mxnet,larroy/mxnet,larroy/mxnet,yajiedesign/mxnet,yajiedesign/mxnet,tlby/mxnet,eric-haibin-lin/mxnet,larroy/mxnet,mbaijal/incubator-mxnet,reminisce/mxnet,sxjscience/mxnet,ptrendx/mxnet,mbaijal/incubator-mxnet,zhreshold/mxnet,yajiedesign/mxnet,mbaijal/incubator-mxnet,eric-haibin-lin/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,leezu/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,sxjscience/mxnet,yajiedesign/mxnet,dmlc/mxnet,tlby/mxnet,tlby/mxnet,larroy/mxnet,DickJC123/mxnet,ForkedReposBak/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,mbaijal/incubator-mxnet,tlby/mxnet,zhreshold/mxnet,eric-haibin-lin/mxnet,mbaijal/incubator-mxnet,leezu/mxnet,mbaijal/incubator-mxnet,leezu/mxnet,apache/incubator-mxnet,zhreshold/mxnet,apache/incubator-mxnet,larroy/mxnet,ForkedReposBak/mxnet,yajiedesign/mxnet,reminisce/mxnet,dmlc/mxnet,reminisce/mxnet,leezu/mxnet,zhreshold/mxnet,reminisce/mxnet,larroy/mxnet,zhreshold/mxnet