Add driver support for Native Client SDK

Add Tool and ToolChain support for clang to target the NaCl OS using the NaCl
SDK for x86-32, x86-64 and ARM.

Includes nacltools::Assemble and Link which are derived from gnutools. They
are similar to Linux but different enought that they warrant their own class.
Also includes a NaCl_TC in ToolChains derived from Generic_ELF with library
and include paths suitable for an SDK and independent of the system tools.

Differential Revision: http://reviews.llvm.org/D8590

llvm-svn: 233594
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 0e99c58..5b01b1c 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2062,6 +2062,9 @@
       else
         TC = new toolchains::Linux(*this, Target, Args);
       break;
+    case llvm::Triple::NaCl:
+      TC = new toolchains::NaCl_TC(*this, Target, Args);
+      break;
     case llvm::Triple::Solaris:
       TC = new toolchains::Solaris(*this, Target, Args);
       break;