Coq now uses .mlg rather than .ml4 (since https://github.com/coq/coq/pull/8763), so we have to ignore its generated dependency files. The `native_compute_profile_*.data` files are generated by `Set NativeCompute Profiling` (see https://github.com/coq/coq/pull/950). Finally `.coq-native` is a directory that may be generated in any subdirectory, not only at top level, so we should not use absolute paths for it.
Add various files that show up when you run tactics (the *.cache in 8.4 and 8.5, .*.cache in 8.6), build plugins (the various OCaml files), and for the native compiler of Coq 8.5.
