Update clang support on recent Haiku

[ Copied from https://llvm.org/bugs/show_bug.cgi?id=26404 ]

clang support on Haiku is lagging a bit, and missing on x86_64.

This patch updates support for x86 and add support for x86_64. It should
apply directly to trunk and it's harmless in the sense that it only
affects Haiku.

Reviewers: rnk, rsmith

Patch by Jérôme Duval

Differential Revision: http://reviews.llvm.org/D16797

llvm-svn: 269201
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 7ff403b..111614f 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2425,6 +2425,9 @@
   ToolChain *&TC = ToolChains[Target.str()];
   if (!TC) {
     switch (Target.getOS()) {
+    case llvm::Triple::Haiku:
+      TC = new toolchains::Haiku(*this, Target, Args);
+      break;
     case llvm::Triple::CloudABI:
       TC = new toolchains::CloudABI(*this, Target, Args);
       break;