Fix non-debug build.

llvm-svn: 238474
diff --git a/lld/COFF/Chunks.cpp b/lld/COFF/Chunks.cpp
index f37e935..18181ac 100644
--- a/lld/COFF/Chunks.cpp
+++ b/lld/COFF/Chunks.cpp
@@ -36,7 +36,8 @@
 }
 
 void SectionChunk::writeTo(uint8_t *Buf) {
-  assert(hasData());
+  if (!hasData())
+    return;
   ArrayRef<uint8_t> Data;
   File->getCOFFObj()->getSectionContents(Header, Data);
   memcpy(Buf + FileOff, Data.data(), Data.size());