Put undefined symbols from shared libraries in the symbol table.

With the recent fixes these symbols have more in common than not with
regular undefined symbols.

llvm-svn: 326242

lld/ELF/InputFiles.cpp

@@ -851,7 +851,10 @@ template <class ELFT> void SharedFile<ELFT>::parseRest() {
 
     StringRef Name = CHECK(Sym.getName(this->StringTable), this);
     if (Sym.isUndefined()) {
-      this->Undefs.insert(Name);
+      Symbol *S = Symtab->addUndefined<ELFT>(Name, Sym.getBinding(),
+                                             Sym.st_other, Sym.getType(),
+                                             /*CanOmitFromDynSym=*/false, this);
+      S->ExportDynamic = true;
       continue;
     }