[tests] add the 'special' dir to the test suite and update it

src/plugins/e-acsl/Makefile.in

src/plugins/e-acsl/tests/special/e-acsl-valid.c

src/plugins/e-acsl/tests/special/oracle/builtin.0.err.oracle

src/plugins/e-acsl/tests/special/oracle/builtin.1.err.oracle

...ins/e-acsl/tests/special/oracle/e-acsl-valid.0.err.oracle

...ins/e-acsl/tests/special/oracle/e-acsl-valid.0.res.oracle

...ins/e-acsl/tests/special/oracle/e-acsl-valid.1.err.oracle

...ins/e-acsl/tests/special/oracle/e-acsl-valid.1.res.oracle

src/plugins/e-acsl/tests/special/oracle/gen_e-acsl-valid.c

src/plugins/e-acsl/tests/special/oracle/gen_e-acsl-valid2.c