Fix uninitialized read of xsl:number token

Found by OSS-Fuzz.

libxslt/numbers.c

@@ -382,6 +382,9 @@ xsltNumberFormatTokenize(const xmlChar *format,
 		tokens->tokens[tokens->nTokens].token = val - 1;
 		ix += len;
 		val = xmlStringCurrentChar(NULL, format+ix, &len);
+	    } else {
+                tokens->tokens[tokens->nTokens].token = (xmlChar)'0';
+                tokens->tokens[tokens->nTokens].width = 1;
             }
 	} else if ( (val == (xmlChar)'A') ||
 		    (val == (xmlChar)'a') ||