Revert "Change calls to xmlCharEncInput to set flush false"

This reverts commit 6e6ae5d which
broke decoding of larger documents with ICU.

See https://bugs.chromium.org/p/chromium/issues/detail?id=820163

HTMLparser.c

@@ -3635,7 +3635,7 @@ htmlCheckEncodingDirect(htmlParserCtxtPtr ctxt, const xmlChar *encoding) {
 	     */
 	    processed = ctxt->input->cur - ctxt->input->base;
 	    xmlBufShrink(ctxt->input->buf->buffer, processed);
-	    nbchars = xmlCharEncInput(ctxt->input->buf, 0);
+	    nbchars = xmlCharEncInput(ctxt->input->buf, 1);
 	    if (nbchars < 0) {
 		htmlParseErr(ctxt, XML_ERR_INVALID_ENCODING,
 		             "htmlCheckEncoding: encoder error\n",

parserInternals.c

@@ -1214,7 +1214,7 @@ xmlSwitchInputEncodingInt(xmlParserCtxtPtr ctxt, xmlParserInputPtr input,
                 /*
                  * convert as much as possible of the buffer
                  */
-                nbchars = xmlCharEncInput(input->buf, 0);
+                nbchars = xmlCharEncInput(input->buf, 1);
             } else {
                 /*
                  * convert just enough to get

xmlIO.c

@@ -3157,7 +3157,7 @@ xmlParserInputBufferPush(xmlParserInputBufferPtr in,
 	 * convert as much as possible to the parser reading buffer.
 	 */
 	use = xmlBufUse(in->raw);
-	nbchars = xmlCharEncInput(in, 0);
+	nbchars = xmlCharEncInput(in, 1);
 	if (nbchars < 0) {
 	    xmlIOErr(XML_IO_ENCODER, NULL);
 	    in->error = XML_IO_ENCODER;
@@ -3273,7 +3273,7 @@ xmlParserInputBufferGrow(xmlParserInputBufferPtr in, int len) {
 	 * convert as much as possible to the parser reading buffer.
 	 */
 	use = xmlBufUse(in->raw);
-	nbchars = xmlCharEncInput(in, 0);
+	nbchars = xmlCharEncInput(in, 1);
 	if (nbchars < 0) {
 	    xmlIOErr(XML_IO_ENCODER, NULL);
 	    in->error = XML_IO_ENCODER;