…uf_limit

The current code creates a situation, where only one record per chunk
 is created. In case of a non-existing ring-buffer, the old mechanism is used.

Also the in_emitter plugin continued to accept records even after the
set emitter_mem_buf_limit was reached. This commit implements a
check if the plugin was paused and returns accordingly.

Signed-off-by: Richard Treu <richard.treu@sap.com>

This commit will pause the inputs (sending to multiline)
to not loose any in-flight records.

Signed-off-by: Richard Treu <richard.treu@sap.com>

This commit will pause the inputs (sending to rewrite_tag)
to not loose any in-flight records.

Signed-off-by: Richard Treu <richard.treu@sap.com>

This commit will pause all known inputs (sending to multiline)
to not loose any in-flight records. in_emitter will keep track
of all sending input plugins and actively pause/resume them
in case in_emitter is paused/resumed.

Signed-off-by: Richard Treu <richard.treu@sap.com>

This commit will add a resume message, when a paused
input plugin is resumed.

Signed-off-by: Richard Treu <richard.treu@sap.com>

…line

This commit will add a test for pause functionality of in_emitter. The test
uses a small emitter buffer size, so the in_emitter will definitely be paused.

Signed-off-by: Richard Treu <richard.treu@sap.com>