target-supports-dg.exp (dg-process-target): Use expr to evaluate the end index in string range.

* lib/target-supports-dg.exp (dg-process-target): Use expr to
evaluate the end index in string range.

From-SVN: r195571

gcc/testsuite/ChangeLog

+2013-01-30  Andreas Schwab  <schwab@suse.de>
+
+	* lib/target-supports-dg.exp (dg-process-target): Use expr to
+	evaluate the end index in string range.
+
 2012-01-30  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/56138

gcc/testsuite/lib/target-supports-dg.exp

@@ -586,7 +586,7 @@ if { [info procs saved-dg-process-target] == [list] } {
 	if [regexp "^target .* xfail .*" $selector] {
 	    set xfail_index [string first "xfail" $selector]
 	    set xfail_selector [string range $selector $xfail_index end]
-	    set target_selector [string range $selector 0 $xfail_index-1]
+	    set target_selector [string range $selector 0 [expr $xfail_index-1]]
 	    set target_selector [string trim $target_selector]
 	    if { [dg-process-target-1 $target_selector] == "N" } {
 		return "N"