Use pkgconfig to detect alsa

configure.ac

@@ -4773,27 +4773,26 @@ dnl  ALSA module
 dnl
 AC_ARG_ENABLE(alsa,
   [  --enable-alsa           ALSA sound support for Linux (default enabled)])
-if test "${enable_alsa}" != "no"
-then
-  AC_CHECK_HEADER(alsa/asoundlib.h, AC_CHECK_LIB(asound, main, have_alsa="true", have_alsa="false"),have_alsa="false")
-  if test "${have_alsa}" = "true"
-  then
-    CFLAGS="${CFLAGS_save}"
-    AC_TRY_COMPILE([#define ALSA_PCM_NEW_HW_PARAMS_API
-                    #define ALSA_PCM_NEW_SW_PARAMS_API
-                    #include <alsa/asoundlib.h>],
-       [snd_pcm_hw_params_get_period_time(0,0,0);],
-        AC_DEFINE(HAVE_ALSA_NEW_API, 1, Define if ALSA is at least rc4))
-    VLC_ADD_PLUGIN([alsa])
-    VLC_ADD_LIBS([alsa],[-lasound -lm -ldl])
-    VLC_ADD_PLUGIN([access_alsa])
-    VLC_ADD_LIBS([access_alsa],[-lasound -lm -ldl])
-  else
-    if test "${enable_alsa}" = "yes"; then
-      AC_MSG_ERROR([Could not find ALSA development headers])
-    fi
-  fi
-fi
+   if test "${enable_alsa}" != "no"
+   then
+     PKG_CHECK_MODULES(ALSA, alsa >= 1.0.21a,
+       [ VLC_ADD_PLUGIN([alsa])
+        VLC_ADD_CFLAGS([alsa],[${ALSA_CFLAGS}])
+	VLC_ADD_LIBS([alsa],[${ALSA_LIBS} -lm -ldl])
+        VLC_ADD_LDFLAGS([alsa],[${ALSA_LDFLAGS}])
+	VLC_ADD_PLUGIN([access_alsa])
+	VLC_ADD_CFLAGS([access_alsa],[${ALSA_CFLAGS}])
+	VLC_ADD_LIBS([access_alsa],[${ALSA_LIBS} -lm -ldl])
+	VLC_ADD_LDFLAGS([access_alsa],[${ALSA_LDFLAGS}])
+
+        AC_TRY_COMPILE([#define ALSA_PCM_NEW_HW_PARAMS_API
+                        #define ALSA_PCM_NEW_SW_PARAMS_API
+                        #include <alsa/asoundlib.h>],
+          [snd_pcm_hw_params_get_period_time(0,0,0);],
+          AC_DEFINE(HAVE_ALSA_NEW_API, 1, Define if ALSA is at least rc4))
+       ],
+       [AC_MSG_WARN(ALSA development headers and library not fond)])
+   fi
 
 dnl
 dnl  win32 waveOut plugin