share/compat.h : Remove duplicate flac_stat definition.

Patch-from: lvqcl <lvqcl.mail@gmail.com>
Use _M_X64 instead of _WIN64.

Patch-from: lvqcl <lvqcl.mail@gmail.com>
Suppress MSVS warnings when compiling for x86-64.

Patch-from: lvqcl <lvqcl.mail@gmail.com>
Add intrinsics version of two lpc functions.

Functions:
- FLAC__fixed_compute_best_predictor
- FLAC__fixed_compute_best_predictor_wide

Patch-from: lvqcl <lvqcl.mail@gmail.com>
Add files missing from commit 93f6109c9016.
src/flac/utils.c : Fix compile guard for ioctl().
libFLAC/stream_encoder.c : Fix if else wibble.

Patch-from: lvqcl <lvqcl.mail@gmail.com>