Fix memory leaks in GoParser

[teemperor]

Summary

The GoParser is leaking memory in the tests due to not freeing allocated nodes when encountering some parsing errors. With this patch all GoParser tests are passing with enabled memory sanitizers/ubsan.

[labath]

It looks like all of these parsing functions would benefit from returning unique_ptr, but that's probably not something we should bother doing now that we are contemplating removing this code.

lldb/trunk/source/Plugins/ExpressionParser/Go/GoParser.cpp

 GoASTExpr *GoParser::CompositeLit() {
   Rule r("CompositeLit", this);
   GoASTExpr *type;
   (type = StructType()) || (type = ArrayOrSliceType(true)) ||
       (type = MapType()) || (type = Name());
   if (!type)
     return r.error();
   GoASTCompositeLit *lit = LiteralValue();
-  if (!lit)
+  if (!lit) {
+    delete type;
     return r.error();
+  }
   lit->SetType(type);
   return lit;
 }
 
 GoASTCompositeLit *GoParser::LiteralValue() {
   if (!match(GoLexer::OP_LBRACE))
     return nullptr;
   std::unique_ptr<GoASTCompositeLit> lit(new GoASTCompositeLit);
if (match(GoLexer::OP_LPAREN)) {
     return call.release();
   }
   return nullptr;
 }
 
 GoASTExpr *GoParser::Conversion() {
   Rule r("Conversion", this);
   if (GoASTExpr *t = Type2()) {
+    std::unique_ptr<GoASTExpr> owner(t);
     if (match(GoLexer::OP_LPAREN)) {
       GoASTExpr *v = Expression();
       if (!v)
         return syntaxerror();
       match(GoLexer::OP_COMMA);
       if (!mustMatch(GoLexer::OP_RPAREN))
         return r.error();
       GoASTCallExpr *call = new GoASTCallExpr(false);
       call->SetFun(t);
+      owner.release();
       call->AddArgs(v);
       return call;
     }
   }
   return r.error();
 }
 
 GoASTExpr *GoParser::Type2() {