bitreader: Add inlined and unchecked versions of the important functions
API: gst_bit_reader_skip_unchecked
API: gst_bit_reader_skip_to_byte_unchecked
API: gst_bit_reader_get_bits_uint16_unchecked
API: gst_bit_reader_get_bits_uint32_unchecked
API: gst_bit_reader_get_bits_uint64_unchecked
API: gst_bit_reader_get_bits_uint8_unchecked
API: gst_bit_reader_peek_bits_uint16_unchecked
API: gst_bit_reader_peek_bits_uint32_unchecked
API: gst_bit_reader_peek_bits_uint64_unchecked
API: gst_bit_reader_peek_bits_uint8_unchecked
This alone makes flacparse about 3 times faster.