configure: add pkg-config check for alsa

Helps with use cases such as static linking, as the .pc file
does actually contain the necessary Libs.private entries for all
required dependencies.

configure

@@ -6268,7 +6268,8 @@ EOF
 fi
 check_header soundcard.h
 
-enabled alsa && check_lib alsa alsa/asoundlib.h snd_pcm_htimestamp -lasound
+enabled alsa && use_pkg_config alsa alsa "alsa/asoundlib.h" snd_pcm_htimestamp ||
+    check_lib alsa alsa/asoundlib.h snd_pcm_htimestamp -lasound
 
 enabled jack && check_lib jack jack/jack.h jack_client_open -ljack &&
     check_func jack_port_get_latency_range -ljack