Revert the r348352 "[clang] - Simplify tools::SplitDebugName."

This partially reverts the r348352 (https://reviews.llvm.org/D55006)
because of https://bugs.llvm.org/show_bug.cgi?id=41161.

I did not revert the test case file because it passes fine now.

llvm-svn: 357061
diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index 0784632..178e7f7 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -826,7 +826,7 @@
   if (Args.hasArg(options::OPT_gsplit_dwarf) &&
       getToolChain().getTriple().isOSLinux())
     SplitDebugInfo(getToolChain(), C, *this, JA, Args, Output,
-                   SplitDebugName(Args, Output));
+                   SplitDebugName(Args, Inputs[0], Output));
 }
 
 namespace {