patch Charles Bozeman for validation of all the date, time, and duration

* xmlschemastypes.c: patch Charles Bozeman for validation of
  all the date, time, and duration types
* test/schemas/dur_0* result/schemas/dur_0*: associated tests
* configure.in: fixed an error pointed by an user
* xml2-config.in: fixed an error pointed by an user
Daniel
diff --git a/xml2-config.in b/xml2-config.in
index 768e336..da31e7f 100644
--- a/xml2-config.in
+++ b/xml2-config.in
@@ -8,7 +8,7 @@
 usage()
 {
     cat <<EOF
-Usage: xml-config [OPTION]
+Usage: xml2-config [OPTION]
 
 Known values for OPTION are:
 
@@ -38,6 +38,8 @@
     case "$1" in
     --prefix=*)
 	prefix=$optarg
+	includedir=$prefix/include
+	libdir=$prefix/lib
 	;;
 
     --prefix)