[lld] r277532 - Support expressions inside FLAGS.

[George Rimar via llvm-commits]

>+        // Passing 0 for the value of dot is a bit of a hack. It means that
>+        // we accept expressions like ".|1".
>+        PhdrCmd.Flags = readExpr()(0);

I think something like D23062 could help here.
Or like Rui mentioned in comments for D23063, such checks (disallow using dot) probably
should be done at parcing time. It is not the single place where we might want
to restrict using of ".".

George.