Reland r311836 - [Driver] Use arch type to find compiler-rt libraries (on Linux)

Use llvm::Triple::getArchTypeName() when looking for compiler-rt
libraries, rather than the exact arch string from the triple. This is
more correct as it matches the values used when building compiler-rt
(builtin-config-ix.cmake) which are the subset of the values allowed
in triples.

For example, this fixes an issue when the compiler set for
i686-pc-linux-gnu triple would not find an i386 compiler-rt library,
while this is the exact arch that is detected by compiler-rt. The same
applies to any other i?86 variant allowed by LLVM.

This also makes the special case for MSVC unnecessary, since now i386
will be used reliably for all 32-bit x86 variants.

Differential Revision: https://reviews.llvm.org/D26796

llvm-svn: 311923
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 0476d15..2660c5a 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -297,15 +297,12 @@
   const llvm::Triple &Triple = TC.getTriple();
   bool IsWindows = Triple.isOSWindows();
 
-  if (Triple.isWindowsMSVCEnvironment() && TC.getArch() == llvm::Triple::x86)
-    return "i386";
-
   if (TC.getArch() == llvm::Triple::arm || TC.getArch() == llvm::Triple::armeb)
     return (arm::getARMFloatABI(TC, Args) == arm::FloatABI::Hard && !IsWindows)
                ? "armhf"
                : "arm";
 
-  return TC.getArchName();
+  return llvm::Triple::getArchTypeName(TC.getArch());
 }
 
 std::string ToolChain::getCompilerRTPath() const {