[Cin] [PATCH] [buildsystem] patch for building nasm 2.14.02 as thirdparty app

This patch adds in somewhat hackish way support for building nasm as part of thirdparty/ tree, combined with earlier openjpeg-2.4.0 patch. It worked without autgen.sh on my machine, but if you use github [0] tarballs ./autogen.sh step is needed. Also, dav1d-0.5.1 patch hardcoded nasm path to /usr/bin/nasm I un-hardcoded it, so it actually can be build with newly-compiled nasm ... seems to work on Ubuntu 16.04.7 amd64 ? At least simple ./configure doesn't fail in dav1d dir .... [0] https://github.com/netwide-assembler/nasm/archive/nasm-2.14.02.tar.gz also you can get xz traball from https://sources.voidlinux-ppc.org/nasm-2.14.02/ {one can wonder why one need x86 asm on PPC, but may be for cross-compiling}