lib: do not forget to initialize TLS keys for output plugins (#1862)
lib: do not forget to initialize TLS keys for output plugins (#1862)

I noticed that unit tests for macOS were failing on Travis CI with
the following error message.

    No output has been received in the last 10m0s, this potentially
    indicates a stalled build or something wrong with the build itself.

It turned out that we introduced a new TLS variable in 30d271ea,
but never added a code path to initialized it. This was causing
runtime test programs to deadlock on flb_start().

This should fix it.

Signed-off-by: Fujimoto Seiji <ef879192bb1e41d519c82cf76440dc8e9a530806@clear-code.com>
nokute78/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,nokute78/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,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,fluent/fluent-bit,fluent/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit,nokute78/fluent-bit