add comments from vsl.h to explain the DISPATCH_* defines

src/child.c

@@ -75,6 +75,25 @@
 #define REQEND_T_VAR "req_endt"
 #define REQEND_T_LEN (sizeof(REQEND_T_VAR "=1430176881.682097"))
 
+/*
+ * from vsl.h
+ *
+ * VSLQ_Dispatch
+ * Return values:
+ *     1: Call again
+ *     0: No more log records available
+ *   !=0: The error code from VSL_Next() or func returned non-zero
+ *
+ * VSL_Next()
+ * Return values:
+ *      1:      Cursor points to next log record
+ *      0:      End of log
+ *     -1:      End of file
+ *     -2:      Remote abandoned or closed
+ *     -3:      Overrun
+ *     -4:      I/O read error - see errno
+ */
+
 #define DISPATCH_EOL 0
 #define DISPATCH_RETURN_OK 0
 #define DISPATCH_CONTINUE 1