Fix gnat.dg testing with linker plugin check

	* lib/gcc-dg.exp (GCC_UNDER_TEST): Set before calling
	check_linker_plugin_available.

From-SVN: r180300

gcc/testsuite/ChangeLog

+2011-10-21  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* lib/gcc-dg.exp (GCC_UNDER_TEST): Set before calling
+	check_linker_plugin_available.
+
 2011-10-21  Kai Tietz  <ktietz@redhat.com>
 
 	* gcc.target/i386/branch-cost1.c: New test.

gcc/testsuite/lib/gcc-dg.exp

@@ -41,6 +41,11 @@ if { [ishost "*-*-cygwin*"] } {
   setenv LANG C.ASCII
 }
 
+global GCC_UNDER_TEST
+if ![info exists GCC_UNDER_TEST] {
+    set GCC_UNDER_TEST "[find_gcc]"
+}
+
 if [info exists TORTURE_OPTIONS] {
     set DG_TORTURE_OPTIONS $TORTURE_OPTIONS
 } else {
@@ -84,12 +89,6 @@ if [check_effective_target_lto] {
     }
 }
 
-
-global GCC_UNDER_TEST
-if ![info exists GCC_UNDER_TEST] {
-    set GCC_UNDER_TEST "[find_gcc]"
-}
-
 global orig_environment_saved
 
 # This file may be sourced, so don't override environment settings