Convert assert(0) to llvm_unreachable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149967 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 50a5f8d..6d53fb1 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -600,7 +600,7 @@
 }
 
 void MCStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol) {
-  assert(0 && "This file format doesn't support this directive");
+  llvm_unreachable("This file format doesn't support this directive");
 }
 
 void MCStreamer::EmitFnStart() {