engine: fix segfault on invalid output configuration
engine: fix segfault on invalid output configuration

The following configuration causes memory crash:

    [Output]
      Name File
      Patt /var/log/test.log

The reason is that Fluent Bit ignores the error return from
`flb_output_init_all()`, and boldly proceeds into the main loop
without output plugins being initialized.

Fix the return code check so that it can exit on error properly.

Signed-off-by: Fujimoto Seiji <ef879192bb1e41d519c82cf76440dc8e9a530806@ceptord.net>

nokute78/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit