Initialize dot.

This would fix an initialized error found by msan. The error is not
showing after r298241, but it is not clear why.

llvm-svn: 298251

lld/ELF/LinkerScript.cpp

@@ -430,6 +430,7 @@ void LinkerScriptBase::processCommands(OutputSectionFactory &Factory) {
   Aether = make<OutputSection>("", 0, SHF_ALLOC);
   Aether->SectionIndex = 1;
   CurOutSec = Aether;
+  Dot = 0;
 
   for (unsigned I = 0; I < Opt.Commands.size(); ++I) {
     auto Iter = Opt.Commands.begin() + I;