Expose the sbuf_putbuf() symbol to libsbuf. There are a few other symbols

that are present but not exposed, like get/set/clear flags, not sure if they
need to be exposed at this point.

Sponsored by:	Netflix

lib/libsbuf/Symbol.map

@@ -31,3 +31,8 @@ FBSD_1.3 {
 FBSD_1.4 {
 	sbuf_hexdump;
 };
+
+FBSD_1.5 {
+	sbuf_putbuf;
+};
+

lib/libsbuf/Version.def

@@ -8,3 +8,6 @@ FBSD_1.3 {
 
 FBSD_1.4 {
 } FBSD_1.3;
+
+FBSD_1.5 {
+} FBSD_1.4;