[mips][mips64r6] Add support for mips-img-linux-gnu GCC toolchains

Summary:
* Support the multilib layout used by the mips-img-linux-gnu
* Recognize mips{,64}{,el}-img-linux-gnu as being aliases of mips-img-linux-gnu
* Use the correct dynamic linker for mips-img-linux-gnu
* Make mips32r6/mips64r6 the default CPU for mips-img-linux-gnu

Subscribers: mpf

Differential Revision: http://reviews.llvm.org/D4436

llvm-svn: 212719
diff --git a/clang/lib/Driver/Tools.h b/clang/lib/Driver/Tools.h
index c4e6d6c..bc7f58b 100644
--- a/clang/lib/Driver/Tools.h
+++ b/clang/lib/Driver/Tools.h
@@ -218,7 +218,7 @@
 
 namespace mips {
   bool hasMipsAbiArg(const llvm::opt::ArgList &Args, const char *Value);
-  bool isNaN2008(const llvm::opt::ArgList &Args);
+  bool isNaN2008(const llvm::opt::ArgList &Args, const llvm::Triple &Triple);
 }
 
 namespace darwin {