Make use of the --with-expat-dir configure option

ext/xml/config.m4

@@ -15,8 +15,11 @@ fi
 PHP_ARG_ENABLE(xml,for XML support,
 [  --disable-xml           Disable XML support using bundled expat lib], yes)
 
-if test "$PHP_XML" != "no"; then
-  if test "$PHP_XML" = "yes"; then
+PHP_ARG_WITH(expat-dir, external libexpat install dir,
+[  --with-expat-dir=DIR    XML: external libexpat install dir])
+
+if test "$PHP_XML" = "yes" -a "$PHP_EXPAT_DIR" = "no"; then
+
     AC_DEFINE(HAVE_LIBEXPAT, 1, [ ])
     AC_DEFINE(HAVE_LIBEXPAT_BUNDLED, 1, [ ])
     XML_CPPFLAGS=-DXML_BYTE_ORDER=$order
@@ -29,19 +32,24 @@ if test "$PHP_XML" != "no"; then
     PHP_EXTENSION(xml, $ext_shared)
     LIB_BUILD($ext_builddir/expat,$ext_shared,yes)
     PHP_ADD_INCLUDE($ext_srcdir/expat)
-    PHP_FAST_OUTPUT($ext_builddir/expat/Makefile)
-  else
-    EXPAT_DIR=$withval
-    if test -f $EXPAT_DIR/lib/libexpat.a -o -f $EXPAT_DIR/lib/libexpat.so ; then
-        AC_DEFINE(HAVE_LIBEXPAT, 1, [ ])
-        PHP_ADD_INCLUDE($EXPAT_DIR/include)
-    else
-        AC_MSG_RESULT(not found)
-        AC_MSG_ERROR(Please reinstall the expat distribution)
+    PHP_FAST_OUTPUT($ext_builddir/expat/Makefile $ext_builddir/expat/xmlparse/Makefile $ext_builddir/expat/xmltok/Makefile)
+
+else
+  
+  PHP_EXTENSION(xml, $ext_shared)
+  PHP_SUBST(EXPAT_SHARED_LIBADD)
+  AC_DEFINE(HAVE_LIBEXPAT,  1, [ ])
+
+  for i in $PHP_XML $PHP_EXPAT_DIR; do
+    if test -f $i/lib/libexpat.a -o -f $i/lib/libexpat.s? ; then
+      EXPAT_DIR=$i
     fi
+  done
 
-    PHP_SUBST(EXPAT_SHARED_LIBADD)
-    PHP_ADD_LIBRARY_WITH_PATH(expat, $EXPAT_DIR/lib, EXPAT_SHARED_LIBADD)
-    PHP_EXTENSION(xml, $ext_shared)
+  if test -z "$EXPAT_DIR"; then
+    AC_MSG_ERROR(not found. Please reinstall the expat distribution.)
   fi
+
+  PHP_ADD_INCLUDE($EXPAT_DIR/include)
+  PHP_ADD_LIBRARY_WITH_PATH(expat, $EXPAT_DIR/lib, EXPAT_SHARED_LIBADD)
 fi