[ci] Update linux environment

Azure pipelines removed 16.04

other/azure-pipelines/build-linux.yml

@@ -1,6 +1,6 @@
 parameters:
   name: 'BuildLinux'
-  vmImage: 'ubuntu-16.04'
+  vmImage: 'ubuntu-18.04'
   container: 'debian:stretch'
   arch: '' # set it to i386 fof 32-bit build
   buildSystem: 'cmake' # either 'cmake' or 'make'