LTO plugin with older gcc

[Alan Modra]

This works better.

	* ld-plugin/lto.exp: Use gcc -print-file-name to find lto plugin.

diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 7ff5bfb..3a4f661 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -45,7 +45,7 @@ set plugin_names {
 }
 set plug_opt ""
 foreach plug $plugin_names {
-    set plug_so [run_host_cmd $CC "--print-prog-name $plug"]
+    set plug_so [run_host_cmd $CC "--print-file-name $plug"]
     if { $plug_so ne $plug } then {
 	set plug_opt "--plugin $plug_so"
 	break

-- 
Alan Modra
Australia Development Lab, IBM