Use 8x16c wrappers with x86 asm functions for 4:2:2 with high bit depth
Fix uninitialized variable

Caused if the timebase is not specified in stats file. Found by Clang.
Fix ARM asm compilation with Apple assembler
CLI: Avoid redundant 16-bit upconversions in piped raw input

It's not possible to seek in pipes, so if we want to skip frames we have to read and
discard unused ones. It's pointless to do bit-depth upconversions in those frames.