Revert "[WebAssembly] Error on mismatched function signature in final output"

This caused a lot of issues on the WebAssembly waterfall.
In particular, until with the signature of `main`.  We
probably want a better solution for main before we re-land.

Reverts rL335192

llvm-svn: 335355
diff --git a/lld/wasm/MarkLive.cpp b/lld/wasm/MarkLive.cpp
index c9dbbf5..018b325 100644
--- a/lld/wasm/MarkLive.cpp
+++ b/lld/wasm/MarkLive.cpp
@@ -34,6 +34,9 @@
 using namespace lld::wasm;
 
 void lld::wasm::markLive() {
+  if (!Config->GcSections)
+    return;
+
   LLVM_DEBUG(dbgs() << "markLive\n");
   SmallVector<InputChunk *, 256> Q;
 
@@ -42,8 +45,6 @@
       return;
     LLVM_DEBUG(dbgs() << "markLive: " << Sym->getName() << "\n");
     Sym->markLive();
-    if (Sym->SignatureMismatch)
-      error("function signature mismatch: " + Sym->getName());
     if (InputChunk *Chunk = Sym->getChunk())
       Q.push_back(Chunk);
   };