Merge branch 'test-nix' into 'master'

.gitlab-ci.yml

Makefile

Makefile.generating

default.nix

nix/default.nix

nix/empty

nix/frama-ci.nix

nix/frama-ci.sh

share/META.frama-c

share/Makefile.config.in

share/Makefile.dynamic

share/Makefile.dynamic_config.external

share/Makefile.dynamic_config.internal

share/Makefile.plugin.template

src/kernel_internals/runtime/config.ml.in

src/kernel_internals/runtime/config.mli

src/kernel_internals/typing/cabs2cil.ml

src/kernel_services/ast_queries/file.ml

src/kernel_services/plugin_entry_points/dynamic.ml

src/kernel_services/plugin_entry_points/plugin.ml