Revert "Simplify mad detection"

mad.pc is a nice debian addition... Pfff @ other distros.

This reverts commit c5a8c459.

configure.ac

@@ -2736,7 +2736,60 @@ fi
 dnl
 dnl  mad plugin
 dnl
-PKG_ENABLE_MODULES_VLC([mad], [mpgatofixed32], [mad], [MPEG Audio Decoder], [auto])
+AC_ARG_ENABLE(mad,
+  [  --enable-mad            libmad module (default enabled)])
+if test "${enable_mad}" != "no"
+then
+  AC_ARG_WITH(mad,
+    [    --with-mad=PATH       path to libmad],[],[])
+  if test "${with_mad}" != "no" -a -n "${with_mad}"
+  then
+    VLC_ADD_CPPFLAGS([mpgatofixed32],[-I${with_mad}/include])
+    VLC_ADD_LIBS([mpgatofixed32],[-L${with_mad}/lib])
+  fi
+
+  AC_ARG_WITH(mad-tree,
+    [    --with-mad-tree=PATH   mad tree for static linking],[],[])
+  if test "${with_mad_tree}" != "no" -a -n "${with_mad_tree}"
+  then
+    real_mad_tree="`cd ${with_mad_tree} 2>/dev/null && pwd`"
+    if test -z "${real_mad_tree}"
+    then
+      dnl  The given directory can't be found
+      AC_MSG_RESULT(no)
+      AC_MSG_ERROR([${with_mad_tree} directory doesn't exist])
+    fi
+    dnl  Use a custom libmad
+    AC_MSG_CHECKING(for mad.h in ${real_mad_tree})
+    if test -f ${real_mad_tree}/mad.h
+    then
+      AC_MSG_RESULT(yes)
+      VLC_ADD_CPPFLAGS([mpgatofixed32],[-I${real_mad_tree}])
+      VLC_ADD_LIBS([mpgatofixed32],[-L${real_mad_tree}/.libs])
+      LDFLAGS="${LDFLAGS_save} ${LIBS_mpgatofixed32}"
+      AC_CHECK_LIB(mad, mad_bit_init, [
+        VLC_ADD_PLUGIN([mpgatofixed32])
+        VLC_ADD_LIBS([mpgatofixed32],[-lmad])
+        ],[ AC_MSG_ERROR([the specified tree hasn't been compiled ])
+      ],[])
+      LDFLAGS="${LDFLAGS_save}"
+    else
+      AC_MSG_RESULT(no)
+      AC_MSG_ERROR([the specified tree doesn't have mad.h])
+    fi
+  else
+    CPPFLAGS="${CPPFLAGS_save} ${CPPFLAGS_mpgatofixed32}"
+    LDFLAGS="${LDFLAGS_save} ${LIBS_mpgatofixed32}"
+    AC_CHECK_HEADERS(mad.h, ,
+      [ AC_MSG_ERROR([Could not find libmad on your system: you may get it from http://www.underbit.com/products/mad/. Alternatively you can use --disable-mad to disable the mad plugin.]) ])
+    AC_CHECK_LIB(mad, mad_bit_init, [
+      VLC_ADD_PLUGIN([mpgatofixed32])
+      VLC_ADD_LIBS([mpgatofixed32],[-lmad])],
+      [ AC_MSG_ERROR([Cannot find libmad library...]) ])
+    CPPFLAGS="${CPPFLAGS_save}"
+    LDFLAGS="${LDFLAGS_save}"
+  fi
+fi
 
 dnl
 dnl   libid3tag support (FIXME!!! doesn't work with new input)