[perl #40523] [TODO] adjust string_append function and usage

[via RT]

# New Ticket Created by  Leopold Toetsch 
# Please include the string:  [perl #40523]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=40523 >


The C<Uflags> argument in:

STRING *
string_append(Interp *interpreter,
    STRING *a, STRING *b /*NN*/, UINTVAL Uflags)

is totally unused and I've no clue, for what it shall be used.
Please remove it in all usage of string_append.

Thanks,
leo