Use the InstalledDir correctly, and test it correctly as well. =/ Should
have noticed this previously, sorry.

llvm-svn: 141167
diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index 0e9dcd1..eab76d5 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -1589,7 +1589,7 @@
                                          D.PrefixDirs.end());
     Prefixes.push_back(D.SysRoot);
     Prefixes.push_back(D.SysRoot + "/usr");
-    Prefixes.push_back(D.InstalledDir);
+    Prefixes.push_back(D.InstalledDir + "/..");
 
     // Loop over the various components which exist and select the best GCC
     // installation available. GCC installs are ranked by version number.