#371 warning in readers.c with debugging enabled

[manx]

src\libmpg123\readers.c(735,3): warning C4477: 'fprintf' : format string '%td' requires an argument of type 'int', but variadic argument 7 has type 'int64_t'`

patch attached

[Thomas Orgis]

Ok, been a long time. Stuff happened in real life. I finally integrated this. Thanks (though: gcc 11.4 saw no issue with this).