topology: Support widgets' stream name and file inclusion for text conf file

From: Mengdong Lin <[email protected]>

This series doesn't require or cause any ABI updates. It doesn't need the kernel patches that trying to udpate ABI from v4 or v5.

Patch 1 fixes a missing topology feature for text conf file to configure
stream name of a widget.

Patch 2 allows alsaconf to search included files under global
configuration directories. This will benefit topology and UCM.

Patch 3 adds document about how to include files for topology
configuration. There is no c code change but actually it depends on patch 2.

History:
v2: No longer use topology-specific code to support searching included
files, but extend alsaconf to support this and user can just use alsaconf syntax <xxx> and <confdir:xxx>.

v3: Not use <confdir:xxx>, but define new syntax <searchdir:xxx> to
define directories for searching included file.

v4: Not use doxygen comments for static functins. Fix memory leak,
Use snprintf to avoid overflow, use auto variable to cook file path, and list_for_each for non-deletion cases.

Mengdong Lin (3):
topology: Fix missing stream name of widgets in text conf file
alsaconf: Search included files under user specified configuration
directories
topology: Add doc for including other files in the text conf file

 include/topology.h  |  31 ++++++++++
 src/conf.c          | 159 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/topology/dapm.c |  10 ++++
 3 files changed, 199 insertions(+), 1 deletion(-)

2.5.0