Rework r183728, suppress assert(0) for now. Its behavior depends on assertions on win32 hosts.

FIXME: Introduce yet another checker but assert(0).
llvm-svn: 183736
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 1f0f9eb..8baa3a6 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -680,8 +680,11 @@
     return new DarwinARMAsmBackend(T, TT, CS);
   }
 
+#if 0
+  // FIXME: Introduce yet another checker but assert(0).
   if (TheTriple.isOSBinFormatCOFF())
-    llvm_unreachable("Windows not supported on ARM");
+    assert(0 && "Windows not supported on ARM");
+#endif
 
   uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(Triple(TT).getOS());
   return new ELFARMAsmBackend(T, TT, OSABI);