[RESEDN PATCH v2] selftests: introduce additional eventfd test coverage

Add several new test cases which assert corner cases on the eventfd mechanism, for example, the supplied buffer is less than 8 bytes, attempting to write a value that is too large, etc. ./eventfd_test # Starting 9 tests from 1 test cases. # RUN

[PATCH v2] selftests: introduce additional eventfd test coverage

Add several new test cases which assert corner cases on the eventfd mechanism, for example, the supplied buffer is less than 8 bytes, attempting to write a value that is too large, etc. ./eventfd_test # Starting 9 tests from 1 test cases. # RUN