fggets() is overkill for parsing the blocklist

[charles]

fgets() is faster than fggets(), which uses fgetc() under the covers for every single character, and involves a malloc + free call for each line.

This is unnecessary -- we can preallocate a large enough buffer for any blocklist line. And if a line is longer than (to pick a number out of the air) 2048 characters, then line is corrupt and will be thrown away anyway, so in that situation fggets() still doesn't return any extra value.

Also this is the only place where fggets() is used in libtransmission, so we could also remove ggets.[ch].

[charles]

patch applied to trunk by r10754.