dtdocbook/instant has been modified to use a more modern Tcl (8.6),
which means certain functions are not present when we are using the
dtdocbook/tcl (7.5) version of tcl instead of a modern system version.
So, create some defines that should work around this problem.
EXTERN int Tcl_Write _ANSI_ARGS_((Tcl_Channel chan,
char *s, int slen));
+/* JET 8/2018
+ *
+ * dtdocbook/instant has been modified to use a more modern Tcl (8.6),
+ * which means certain functions are not present when we are using the
+ * dtdocbook/tcl (7.5) version of tcl instead of a modern system
+ * version. So, create some defines that should work around this
+ * problem.
+ */
+
+#define Tcl_Alloc(n) malloc(n)
+#define Tcl_Free(p) free(p)
+
+#define Tcl_GetStringResult(i) ((i)->result)
+#define Tcl_GetErrorLine(i) ((i)->errorLine)
+
#endif /* _TCL */