MC: restore behaviour of defaulting to ELF

This restores the previous behaviour of just assuming that if you dont specify a
valid triple that you really meant the default triple with an ELF object file.

llvm-svn: 207349
diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index efdf677..ba132f4 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -780,10 +780,9 @@
       (T.isOSDarwin() || T.isOSBinFormatMachO())) {
     Env = IsMachO;
     InitMachOMCObjectFileInfo(T);
-  } else if (T.isOSWindows() && T.getObjectFormat() == Triple::COFF) {
-    assert((Arch == Triple::x86 || Arch == Triple::x86_64 ||
-            Arch == Triple::arm || Arch == Triple::thumb) &&
-           "unsupported Windows COFF architecture");
+  } else if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
+              Arch == Triple::arm || Arch == Triple::thumb) &&
+             (T.isOSWindows() && T.getObjectFormat() == Triple::COFF)) {
     Env = IsCOFF;
     InitCOFFMCObjectFileInfo(T);
   } else {