fread & fwrite are defined as taking size_t arguments (an unsigned type),
so stop casting their arguments to a signed int just to confuse things.

Fixes warnings:

AuFileName.c:69:59: warning: implicit conversion loses integer precision: 'unsigned long' to 'int' [-Wshorten-64-to-32]
    size = strlen (name) + strlen(&slashDotXauthority[1]) + 2;
         ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~

AuRead.c:58:44: warning: implicit conversion changes signedness: 'int' to 'size_t' (aka 'unsigned long') [-Wsign-conversion]
        if (fread (data, (int) sizeof (char), (int) len, file) != len) {
            ~~~~~                             ^~~~~~~~~

AuWrite.c:49:46: warning: implicit conversion changes signedness: 'int' to 'size_t' (aka 'unsigned long') [-Wsign-conversion]
    if (fwrite (string, (int) sizeof (char), (int) count, file) != count)
        ~~~~~~                               ^~~~~~~~~~~

Signed-off-by: Alan Coopersmith <alan.coopersm...