Frame header padding bit incorrectly set

[autobalance]

When encoding a 32khz WAV at a bitrate of 48kbps, shine generates a frame header of FF FB 3A C4 instead of the expected FF FB 38 C4; the padding bit is incorrectly being set.

It seems to narrow down to non-associativity of the floating-point calculation of avg_slots_per_frame in layer3.c. The calculation with samplerate=32000 and bitr=48 gives a double of 215.999999999999972... which consequently truncates incorrectly to 215.

Setting whole_slots_per_frame by first truncating to a float before converting to an int:

config->mpeg.whole_slots_per_frame = (int)(float)avg_slots_per_frame;

seems to work now and various other WAV files still convert properly. May not be the best solution however as floating point errors may still occur elsewhere.