applied patch for xsi:nil from Frank Gross, this should fix bug #358125

* xmlschemas.c: applied patch for xsi:nil from Frank Gross, this
  should fix bug #358125
Daniel

svn path=/trunk/; revision=3643
diff --git a/xmlschemas.c b/xmlschemas.c
index f3d0278..f38cdc3 100644
--- a/xmlschemas.c
+++ b/xmlschemas.c
@@ -25951,7 +25951,7 @@
 	    xmlRegExecNextValues(inode->regexCtxt,
 		&nbval, &nbneg, &values[0], &terminal);
 	    ret = xmlRegExecPushString(inode->regexCtxt, NULL, NULL);
-	    if (ret <= 0) {		
+	    if ((ret<0) || ((ret==0) && (!INODE_NILLED(inode)))) {
 		/*
 		* Still missing something.
 		*/