Don't worry about pre-1.0.0 alsa-lib include

Problem reported by Ergus in:
https://lists.gnu.org/r/emacs-devel/2019-08/msg00563.html
* configure.ac (ALSA_SUBDIR_INCLUDE): Do not define.
* src/sound.c: Assume ALSA_SUBDIR_INCLUDE.

configure.ac

@@ -1731,26 +1731,6 @@ if test "${with_sound}" != "no"; then
     ALSA_MODULES="alsa >= $ALSA_REQUIRED"
     EMACS_CHECK_MODULES([ALSA], [$ALSA_MODULES])
     if test $HAVE_ALSA = yes; then
-      SAVE_CFLAGS="$CFLAGS"
-      SAVE_LIBS="$LIBS"
-      CFLAGS="$ALSA_CFLAGS $CFLAGS"
-      LIBS="$ALSA_LIBS $LIBS"
-      AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <asoundlib.h>]], [[snd_lib_error_set_handler (0);]])],
-                      emacs_alsa_normal=yes,
-	            emacs_alsa_normal=no)
-      if test "$emacs_alsa_normal" != yes; then
-        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <alsa/asoundlib.h>]],
-                       [[snd_lib_error_set_handler (0);]])],
-                       emacs_alsa_subdir=yes,
-	             emacs_alsa_subdir=no)
-        if test "$emacs_alsa_subdir" != yes; then
-          AC_MSG_ERROR([pkg-config found alsa, but it does not compile.  See config.log for error messages.])
-        fi
-        ALSA_CFLAGS="$ALSA_CFLAGS -DALSA_SUBDIR_INCLUDE"
-      fi
-
-      CFLAGS="$SAVE_CFLAGS"
-      LIBS="$SAVE_LIBS"
       LIBSOUND="$LIBSOUND $ALSA_LIBS"
       CFLAGS_SOUND="$CFLAGS_SOUND $ALSA_CFLAGS"
       AC_DEFINE(HAVE_ALSA, 1, [Define to 1 if ALSA is available.])

src/sound.c

@@ -72,12 +72,8 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <soundcard.h>
 #endif
 #ifdef HAVE_ALSA
-#ifdef ALSA_SUBDIR_INCLUDE
 #include <alsa/asoundlib.h>
-#else
-#include <asoundlib.h>
-#endif /* ALSA_SUBDIR_INCLUDE */
-#endif /* HAVE_ALSA */
+#endif
 
 /* END: Non Windows Includes */