Provide new accessors for xmlOutputBuffer

To avoid digging into buf->buffer insternal strcuture the two
new entry points xmlOutputBufferGetContent() and
xmlOutputBufferGetSize() should make the ode cleaner.

* include/libxml/xmlIO.h: add two new functions
* xmlIO.c: impement the 2 functions based on the new buffer entry points

include/libxml/xmlIO.h

@@ -245,6 +245,12 @@ XMLPUBFUN xmlOutputBufferPtr XMLCALL
 					 void *ioctx,
 					 xmlCharEncodingHandlerPtr encoder);
 
+/* Couple of APIs to get the output without digging into the buffers */
+XMLPUBFUN const xmlChar * XMLCALL
+        xmlOutputBufferGetContent       (xmlOutputBufferPtr out);
+XMLPUBFUN size_t XMLCALL
+        xmlOutputBufferGetSize          (xmlOutputBufferPtr out);
+
 XMLPUBFUN int XMLCALL	
 	xmlOutputBufferWrite		(xmlOutputBufferPtr out,
 					 int len,

xmlIO.c

@@ -2922,6 +2922,39 @@ xmlOutputBufferCreateBuffer(xmlBufferPtr buffer,
     return(ret);
 }
 
+/**
+ * xmlOutputBufferGetContent:
+ * @out:  an xmlOutputBufferPtr
+ *
+ * Gives a pointer to the data currently held in the output buffer
+ *
+ * Returns a pointer to the data or NULL in case of error
+ */
+const xmlChar *
+xmlOutputBufferGetContent(xmlOutputBufferPtr out) {
+    if ((out == NULL) || (out->buffer == NULL))
+        return(NULL);
+
+    return(xmlBufContent(out->buffer));
+}
+
+/**
+ * xmlOutputBufferGetSize:
+ * @out:  an xmlOutputBufferPtr
+ *
+ * Gives the length of the data currently held in the output buffer
+ *
+ * Returns 0 in case or error or no data is held, the size otherwise
+ */
+size_t
+xmlOutputBufferGetSize(xmlOutputBufferPtr out) {
+    if ((out == NULL) || (out->buffer == NULL))
+        return(0);
+
+    return(xmlBufUse(out->buffer));
+}
+
+
 #endif /* LIBXML_OUTPUT_ENABLED */
 
 /**