[e-acsl:dup_function] replace the copy-visitor by an in-place visit

src/plugins/e-acsl/src/code_generator/injector.ml

src/plugins/e-acsl/src/libraries/gmp_types.ml

src/plugins/e-acsl/src/libraries/gmp_types.mli

src/plugins/e-acsl/src/main.ml

src/plugins/e-acsl/src/project_initializer/dup_functions.ml

src/plugins/e-acsl/src/project_initializer/dup_functions.mli