[e-acsl] improve handling of integer division and modulo

src/plugins/e-acsl/TODO

src/plugins/e-acsl/tests/e-acsl-runtime/arith.i

src/plugins/e-acsl/tests/e-acsl-runtime/lazy.i

...ugins/e-acsl/tests/e-acsl-runtime/oracle/arith.res.oracle

src/plugins/e-acsl/tests/e-acsl-runtime/oracle/gen_arith.c

src/plugins/e-acsl/tests/e-acsl-runtime/oracle/gen_lazy.c

src/plugins/e-acsl/tests/e-acsl-runtime/oracle/gen_ptr.c

...lugins/e-acsl/tests/e-acsl-runtime/oracle/lazy.res.oracle

...plugins/e-acsl/tests/e-acsl-runtime/oracle/ptr.res.oracle

src/plugins/e-acsl/tests/e-acsl-runtime/ptr.i

src/plugins/e-acsl/visit.ml