This patch removes FLAC__lpc_restore_signal_16_intrin_sse2().

It's faster than C code, but not faster than MMX-accelerated
ASM functions. It's also slower than the new SSE4.1 functions
that were added by the previous patch.
So this function wasn't very useful before, and now it's
even less useful. I don't see a reason to keep it.

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