[tests] remove directory 'no-main'

src/plugins/e-acsl/tests/no-main/empty.i

-/* run.config
-   COMMENT: empty file
-*/

src/plugins/e-acsl/tests/no-main/oracle/empty.res.oracle

-[kernel] Parsing FRAMAC_SHARE/e-acsl/e_acsl_gmp_api.h (with preprocessing)
-[kernel] Parsing FRAMAC_SHARE/e-acsl/e_acsl.h (with preprocessing)
-[kernel] Parsing tests/no-main/empty.i (no preprocessing)
-[e-acsl] beginning translation.
-[e-acsl] Warning: cannot find entry point `main'.
-  Please use option `-main' for specifying a valid entry point.
-  The generated program may miss memory instrumentation
-  if there are memory-related annotations.
-[e-acsl] translation done in project "e-acsl".

src/plugins/e-acsl/tests/no-main/test_config

-OPT: -e-acsl-check -check -e-acsl