audio: probe audio drivers by default

Add the drivers listed in audio_possible_drivers to audio_drv_list,
using the try-* variants.  That way the probable drivers are compiled by
default if possible.

Additioal tweaks:
  linux: reorder to: pa alsa sdl oss.
  *bsd: drop pa.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Message-id: 20190124112055.547-7-kraxel@redhat.com

configure

@@ -794,13 +794,13 @@ MINGW32*)
 ;;
 GNU/kFreeBSD)
   bsd="yes"
-  audio_drv_list="oss"
+  audio_drv_list="oss try-sdl"
   audio_possible_drivers="oss sdl pa"
 ;;
 FreeBSD)
   bsd="yes"
   make="${MAKE-gmake}"
-  audio_drv_list="oss"
+  audio_drv_list="oss try-sdl"
   audio_possible_drivers="oss sdl pa"
   # needed for kinfo_getvmmap(3) in libutil.h
   LIBS="-lutil $LIBS"
@@ -813,14 +813,14 @@ FreeBSD)
 DragonFly)
   bsd="yes"
   make="${MAKE-gmake}"
-  audio_drv_list="oss"
+  audio_drv_list="oss try-sdl"
   audio_possible_drivers="oss sdl pa"
   HOST_VARIANT_DIR="dragonfly"
 ;;
 NetBSD)
   bsd="yes"
   make="${MAKE-gmake}"
-  audio_drv_list="oss"
+  audio_drv_list="oss try-sdl"
   audio_possible_drivers="oss sdl"
   oss_lib="-lossaudio"
   HOST_VARIANT_DIR="netbsd"
@@ -845,7 +845,7 @@ Darwin)
     LDFLAGS="-arch x86_64 $LDFLAGS"
   fi
   cocoa="yes"
-  audio_drv_list="coreaudio"
+  audio_drv_list="coreaudio try-sdl"
   audio_possible_drivers="coreaudio sdl"
   LDFLAGS="-framework CoreFoundation -framework IOKit $LDFLAGS"
   libs_softmmu="-F/System/Library/Frameworks -framework Cocoa -framework IOKit $libs_softmmu"
@@ -861,7 +861,7 @@ SunOS)
   install="${INSTALL-ginstall}"
   smbd="${SMBD-/usr/sfw/sbin/smbd}"
   if test -f /usr/include/sys/soundcard.h ; then
-    audio_drv_list="oss"
+    audio_drv_list="oss try-sdl"
   fi
   audio_possible_drivers="oss sdl"
 # needed for CMSG_ macros in sys/socket.h
@@ -879,7 +879,7 @@ Haiku)
   LIBS="-lposix_error_mapper -lnetwork $LIBS"
 ;;
 Linux)
-  audio_drv_list="oss"
+  audio_drv_list="try-pa try-alsa try-sdl oss"
   audio_possible_drivers="oss alsa sdl pa"
   linux="yes"
   linux_user="yes"