sprint_error_report: call sprint_call_stack() for robot

- Turns out that a call stack can be useful for debug even when done
  from a robot program.

Change-Id: I89bb80ccc4b92e9f87816d1e73730b3686fe68dc
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/lib/gen_print.py b/lib/gen_print.py
index 59eeea6..dd36d70 100755
--- a/lib/gen_print.py
+++ b/lib/gen_print.py
@@ -1334,8 +1334,7 @@
     caller_func_name = sprint_func_name(2)
     if caller_func_name.endswith("print_error_report"):
         stack_frame_ix += 1
-    if not robot_env:
-        buffer += sprint_call_stack(indent, stack_frame_ix)
+    buffer += sprint_call_stack(indent, stack_frame_ix)
     buffer += sprint_pgm_header(indent)
     buffer += sprint_dashes(width=120, char="=")