CI: huge linux builds should also run syntax & indent tests

closes: #15960

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/testdir/runtest.vim b/runtime/syntax/testdir/runtest.vim
index 2fba6a6..7113602 100644
--- a/runtime/syntax/testdir/runtest.vim
+++ b/runtime/syntax/testdir/runtest.vim
@@ -431,7 +431,7 @@
     call Message('View generated screendumps with "../../src/vim --clean -S testdir/viewdumps.vim"')
   endif
 
-  call AppendMessages('== SUMMARY ==')
+  call AppendMessages('== SUMMARY SYNTAX TESTS ==')
 
   if len(failed_tests) > 0
     " have make report an error