Don't gen precedence predicate for left-recur X+ loops

[parrt]

block_statements :
     block_statement |
     block_statements block_statement;

generates

block_statements[int _p]
    :   ( {} block_statement
        )
        ( options{preventepsilon=true;}:
          {1 >= $_p}? block_statement
        )*
    ;

but that could be

block_statements[int _p]
    :   ( {} block_statement
        )
        ( block_statement )*
    ;

or

block_statements[int _p]
    :   block_statement+
    ;

[sharwell]

Assigned to 4.x. This is one of the standard optimizations I want to support during code generation once we are using ANTLR 4 grammars inside the ANTLR 4 tool itself.

[parrt]

yeah, i want to do the other ATN shrinkage stuff you have too