Fix -ftrap-function fallout from llvm r145714.  <rdar://problem/10799325>

That llvm change removed the -trap-func backend option, so that using
-ftrap-function with clang would cause the backend to complain.  Fix it
by adding the trap function name to the CodeGenOptions and passing it through
to the TargetOptions.

llvm-svn: 149679
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 97c3c69..93dcd0d 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1947,12 +1947,7 @@
     CmdArgs.push_back(A->getValue(Args));
   }
 
-  // Forward -ftrap_function= options to the backend.
-  if (Arg *A = Args.getLastArg(options::OPT_ftrap_function_EQ)) {
-    StringRef FuncName = A->getValue(Args);
-    CmdArgs.push_back("-backend-option");
-    CmdArgs.push_back(Args.MakeArgString("-trap-func=" + FuncName));
-  }
+  Args.AddLastArg(CmdArgs, options::OPT_ftrap_function_EQ);
 
   // -fno-strict-overflow implies -fwrapv if it isn't disabled, but
   // -fstrict-overflow won't turn off an explicitly enabled -fwrapv.