fix for missing Program.symbol definitions

it's relevant only for xdctest

src/targets/gnu/targets/linkcmd.xdt

diff --git a/src/targets/gnu/targets/linkcmd.xdt b/src/targets/gnu/targets/linkcmd.xdt
index 0f15ecb..fdde4b0 100644
--- a/src/targets/gnu/targets/linkcmd.xdt
+++ b/src/targets/gnu/targets/linkcmd.xdt
@@ -37,6 +37,21 @@
 %    }
 %}
 
+/*
+ * symbolic aliases for numeric constants or static instance objects
+ */
+%for (var sym in Program.symbol) {
+    %var inst = Program.symbol[sym];
+    %if (typeof(inst) == 'number') {
+`this.build.target.asmName(sym)` = `inst`;
+    %}
+    %else {
+        %var objTab = inst.$module.$name.replace(/\./g, '_') + '_Object__table__V';
+        %var off = Program.$capsule.instSize(inst) * inst.$index;
+`this.build.target.asmName(sym)` = `this.build.target.asmName(objTab)` + `off`;
+    %}
+%}
+
 %if ($args.length > 0) {
 /* input libraries */
 INPUT(