Thankfully I already redundantly edited this file myself before to
account for updates in the source, and backed this up to another
location just in case the shell script breaks my build files,
which it did!
This revision of libaom has some conflicts with our vendor script
and build system. A number of new .asm files have the same basename
as .c files, which our build system cannot handle.
To work around this, I manually renamed the conflicting
files in the filesystem and sources.mozbuild.
Also add av1_convolve_scale_sse4.c to sources.mozbuild manually.
This is needed by the build but for some reason isn't picked up
by generate_sources_mozbuild.sh.
