ARMv7k: select ABI based on v7k Arch rather than watchos OS.

Various bits we'd like to use the new ABI actually compile with "-arch armv7k
-miphoneos-version-min=9.0". Not ideal, but also not ridiculous given how
slices work.

llvm-svn: 258976
diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index f57d087..4f72a96 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -1075,7 +1075,9 @@
     return false;
 
   // Only watchOS uses the new DWARF/Compact unwinding method.
-  return !isTargetWatchOS();
+  llvm::Triple Triple(ComputeLLVMTriple(Args));
+  return !(Triple.getArchName() == "armv7k" ||
+           Triple.getArchName() == "thumbv7k") && !isTargetWatchOS();
 }
 
 bool MachO::isPICDefault() const { return true; }