gmm : const char* => char* because its value is modified (I think some
assignation are wrong though)

git-svn-id: https://geuz.org/svn/gmsh/trunk@18731 59c8cabf-10d6-4a28-b43f-3936b85956c4
git-svn-id: https://geuz.org/svn/gmsh/trunk@18732 59c8cabf-10d6-4a28-b43f-3936b85956c4
git-svn-id: https://geuz.org/svn/gmsh/trunk@18733 59c8cabf-10d6-4a28-b43f-3936b85956c4
git-svn-id: https://geuz.org/svn/gmsh/trunk@18734 59c8cabf-10d6-4a28-b43f-3936b85956c4