Bump clang's default target CPU for the i386 architecture (aka "x86") to

i686, as per the discussion on the freebsd-arch mailing list.  Earlier
in r352030, I had already bumped it to i586, to work around missing
atomic 64 bit functions for the i386 architecture.

Relnotes:	yes

contrib/llvm/tools/clang/lib/Driver/ToolChains/Arch/X86.cpp

@@ -93,10 +93,11 @@ const char *x86::getX86TargetCPU(const ArgList &Args,
     return "x86-64";
 
   switch (Triple.getOS()) {
+  case llvm::Triple::FreeBSD:
+    return "i686";
   case llvm::Triple::NetBSD:
   case llvm::Triple::OpenBSD:
-    return "i486"; 
-  case llvm::Triple::FreeBSD:
+    return "i486";
   case llvm::Triple::Haiku:
     return "i586";
   default: