Avoid spurious errors if the launcher test symlinks already exist

ChangeLog

@@ -4,6 +4,8 @@
 
 	* testsuite/lib/launcher.exp (link_dejagnu_launcher_test_item):
 	Use [file normalize] to ensure that link targets are unambiguous.
+	(link_dejagnu_launcher_test_item): Avoid spurious errors when test
+	environment has already been prepared in a previous run.
 
 	* testsuite/lib/launcher.exp (link_dejagnu_launcher_test_item):
 	New procedure to collect existing repeated testsuite code.

testsuite/lib/launcher.exp

@@ -76,6 +76,10 @@ proc try_dejagnu_launcher { launcher test } {
 }
 
 proc link_dejagnu_launcher_test_item {link target} {
+    if {[file exists $link]} {
+	verbose -log "   item $link already exists"
+	return
+    }
     verbose -log "linking $link"
     verbose -log "     to $target"
     if {[catch {file link -symbolic $link [file normalize $target]} err]} {