mark libstdc++ tests unsupported if they fail with "relocation truncated"

	* testsuite/lib/libstdc++.exp (libstdc++-dg-test): Check for
	unsupported compiler output.

From-SVN: r228844

libstdc++-v3/ChangeLog

+2015-10-15  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* testsuite/lib/libstdc++.exp (libstdc++-dg-test): Check for
+	unsupported compiler output.
+
 2015-10-13  Nathan Froyd  <froydnj@gcc.gnu.org>
 
 	* config/cpu/i486/opt/bits/opt_random.h: Include pmmintrin.h instead

libstdc++-v3/testsuite/lib/libstdc++.exp

@@ -409,6 +409,11 @@ proc libstdc++-dg-test { prog do_what extra_tool_flags } {
     # and-target file), but the defaults are lacking in goodness.
     set comp_output [$select_compile "$prog" "$output_file" "$compile_type" $options];
 
+    set unsupported_message [libstdc++_check_unsupported_p $comp_output]
+    if { $unsupported_message != "" } {
+	set comp_output "::unsupported::$unsupported_message"
+    }
+
     return [list $comp_output $output_file]
 }