[rfa] remove more alpha plt entries

[Roland McGrath]

> It's sometimes hard to tell when such internal names are *really*
> internal to just libc.so, or whether they're internal to the entire
> glibc package (i.e. used or overridden by pthreads or librt).

You can look at libc.map in your build and see if the symbol is there.
If not, it can be declared with attribute_hidden.  

> IMO it's easier to just not think about it and use the infrastructure
> provided by the libc_hidden_* macros.

That is certainly fine by me if you are fastidious about doing it so it
doesn't break any other port, i.e. you get every unused sysdeps/ file too.
But I don't want everyone to tend toward doing this willy-nilly for lots of
symbols that don't really require it.  It bloats the unstripped symbol
tables, adds another epsilon or two to compilation time, can make
gdb/addr2line a bit more confusing, etc.


Thanks,
Roland