Backport prelink unsupported dwarf version handling from GDB ToT

llvm-svn: 211240
diff --git a/clang-tests-external/gdb/7.5/gdb/testsuite/lib/prelink-support.exp b/clang-tests-external/gdb/7.5/gdb/testsuite/lib/prelink-support.exp
index 08136e0..60db5c8 100644
--- a/clang-tests-external/gdb/7.5/gdb/testsuite/lib/prelink-support.exp
+++ b/clang-tests-external/gdb/7.5/gdb/testsuite/lib/prelink-support.exp
@@ -278,6 +278,11 @@
 	xfail $test
 	return 0
     }
+    if {$result == 1 && [regexp {DWARF [^\r\n]* unhandled} $output]} {
+        # Prelink didn't understand the version of dwarf present.
+        unsupported "$test (dwarf version unhandled)"
+        return 0
+    }
     if {$result == 0 && $output == ""} {
 	pass $test
 	return 1