[master] bfeb331 reserve the error value from VSL_Write() and friends

[Nils Goroll]

commit bfeb3316e349264dc9526391c483da6915cbd861
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon Feb 26 20:20:01 2018 +0100

    reserve the error value from VSL_Write() and friends

diff --git a/include/vapi/vsl.h b/include/vapi/vsl.h
index 9a8d70d..2209ac3 100644
--- a/include/vapi/vsl.h
+++ b/include/vapi/vsl.h
@@ -339,6 +339,7 @@ VSL_Check(const struct VSL_cursor *c, const struct VSLC_ptr *ptr);
 	 */
 
 enum vsl_status {
+	vsl_e_write	= -5,	// Error from VSL_Write etc.
 	vsl_e_io	= -4,	// I/O read error - see errno
 	vsl_e_overrun	= -3,	// Overrun
 	vsl_e_abandon	= -2,	// Remote abandoned or closed