cisco/openh264 — pull request #516 by mstorsjo (2014-03-17 11:28:00+00:00)
Title: Fix building with yasm in 64 bit mode

Use movsxd in SIGN_EXTENSION

This is what nasm ended up assembling movsx with 32 bit input to
anyway.

Keep using plain movsx for 16 bit input.

This fixes building with yasm in 64 bit mode.