alsa-gobject: seq: fix port creation API

alsa-project/alsa-gobject pull request #36 was opened from takaswie:

ALSASeq.UserClient.create_port() has nullable argument for the numerical ID of port to use SNDRV_SEQ_PORT_FLG_GIVEN_PORT flag properly. However, the nullable is not inconvenient for PyGObject and causes SIGSEGV.

This patchset adds an alternative API, ALSASeq.UserClient.create_port_at() for the flag, then ALSASeq.UserClient.create_port() hs no argument for explicit port ID.

Additionally, this patchset includes some fixes for the other parts.

Request URL : https://github.com/alsa-project/alsa-gobject/pull/36 Patch URL : https://github.com/alsa-project/alsa-gobject/pull/36.patch Repository URL: https://github.com/alsa-project/alsa-gobject