fix api_demos


git-svn-id: https://geuz.org/svn/gmsh/trunk@16616 59c8cabf-10d6-4a28-b43f-3936b85956c4


git-svn-id: https://geuz.org/svn/gmsh/trunk@16617 59c8cabf-10d6-4a28-b43f-3936b85956c4