amixer: always use line buffering for (s)events

alsa-project/alsa-utils pull request #306 was opened from elenril:

Line buffering is the obviously correct mode for (s)events, but block buffering would typically be used when piping its output to another program.

Request URL : https://github.com/alsa-project/alsa-utils/pull/306 Patch URL : https://github.com/alsa-project/alsa-utils/pull/306.patch Repository URL: https://github.com/alsa-project/alsa-utils