[libxml2] Fix xmlSchemaGetCanonValue formatting for date and dateTime

[Nick Wellnhofer <nwellnhof src gnome org>]

commit e45e06de90850fcc25b997d921f1703a9be82161
Author: Kevin Puetz <PuetzKevinA JohnDeere com>
Date:   Fri Jan 31 13:16:37 2020 -0600

    Fix xmlSchemaGetCanonValue formatting for date and dateTime
    
    Per https://www.w3.org/TR/xmlschema-2/#dateTime-lexical-representation,
    the date portion is supposed to use '-' as the delimiter

 xmlschemastypes.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/xmlschemastypes.c b/xmlschemastypes.c
index e7764d90..75acb560 100644
--- a/xmlschemastypes.c
+++ b/xmlschemastypes.c
@@ -6003,13 +6003,13 @@ xmlSchemaGetCanonValue(xmlSchemaValPtr val, const xmlChar **retValue)
                    * recoverable timezone and not "Z".
                    */
                    snprintf(buf, 30,
-                       "%04ld:%02u:%02uZ",
+                       "%04ld-%02u-%02uZ",
                        norm->value.date.year, norm->value.date.mon,
                        norm->value.date.day);
                    xmlSchemaFreeValue(norm);
                } else {
                    snprintf(buf, 30,
-                       "%04ld:%02u:%02u",
+                       "%04ld-%02u-%02u",
                        val->value.date.year, val->value.date.mon,
                        val->value.date.day);
                }
@@ -6030,14 +6030,14 @@ xmlSchemaGetCanonValue(xmlSchemaValPtr val, const xmlChar **retValue)
                    * TODO: Check if "%.14g" is portable.
                    */
                    snprintf(buf, 50,
-                       "%04ld:%02u:%02uT%02u:%02u:%02.14gZ",
+                       "%04ld-%02u-%02uT%02u:%02u:%02.14gZ",
                        norm->value.date.year, norm->value.date.mon,
                        norm->value.date.day, norm->value.date.hour,
                        norm->value.date.min, norm->value.date.sec);
                    xmlSchemaFreeValue(norm);
                } else {
                    snprintf(buf, 50,
-                       "%04ld:%02u:%02uT%02u:%02u:%02.14g",
+                       "%04ld-%02u-%02uT%02u:%02u:%02.14g",
                        val->value.date.year, val->value.date.mon,
                        val->value.date.day, val->value.date.hour,
                        val->value.date.min, val->value.date.sec);