[Driver] Support for -save-stats in AddGoldPlugin.

This patch updates AddGoldPlugin to pass stats-file to the Gold plugin,
if -save-stats is passed. It also moves the save-stats option handling
to a helper function tools::getStatsFileName.

Reviewers: tejohnson, mehdi_amini, compnerd

Reviewed By: tejohnson, compnerd

Differential Revision: https://reviews.llvm.org/D45771

llvm-svn: 330422
diff --git a/clang/lib/Driver/ToolChains/FreeBSD.cpp b/clang/lib/Driver/ToolChains/FreeBSD.cpp
index 04b3719..b570245 100644
--- a/clang/lib/Driver/ToolChains/FreeBSD.cpp
+++ b/clang/lib/Driver/ToolChains/FreeBSD.cpp
@@ -231,8 +231,11 @@
   Args.AddAllArgs(CmdArgs, options::OPT_Z_Flag);
   Args.AddAllArgs(CmdArgs, options::OPT_r);
 
-  if (D.isUsingLTO())
-    AddGoldPlugin(ToolChain, Args, CmdArgs, D.getLTOMode() == LTOK_Thin, D);
+  if (D.isUsingLTO()) {
+    assert(!Inputs.empty() && "Must have at least one input.");
+    AddGoldPlugin(ToolChain, Args, CmdArgs, Output, Inputs[0],
+                  D.getLTOMode() == LTOK_Thin);
+  }
 
   bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
   bool NeedsXRayDeps = addXRayRuntime(ToolChain, Args, CmdArgs);