[e-acsl] remove empty oracles

src/plugins/e-acsl/tests/libc/oracle_dev/file.e-acsl.err.log

src/plugins/e-acsl/tests/libc/oracle_dev/mem.e-acsl.err.log

...ugins/e-acsl/tests/libc/oracle_dev/sprintf.e-acsl.err.log

src/plugins/e-acsl/tests/libc/oracle_dev/str.e-acsl.err.log

...lugins/e-acsl/tests/memory/oracle_dev/vdso.e-acsl.err.log