Read multilib requirement on Android rom building and other stuff. About two years absent from getting rid with android rom. I have time to set and dating agin with android rom compiling festival. Firstly, setting-up build environment on Linux distro, ubuntu is the star of android rom compiling world. The critical point is the host must be multilib linux system. I do not well understand linux, since I just a lover and common user. I think by having precompiled 32 bit library in the 64 bit system will be annoying if the package version di not match. AFAIK, Gentoo is one the "easier" linux distro provided opportunity to have consitence system where 32 libs running congruently with 64 libs in a system.Funtoo News provided very comprehensive reading material, and the article have been TWO YEARS old .... LOL.
Thus by setting USE Flag in /etc/portage/make.conf, by adding ABI_X86="32" system will merge all package nicely and build all package in dual libs. The reason only adding ABI_X86="32" instead of ABI_X86="32 64", my system is amd64 multilib, thus ABI_X86=64 is explicitly build in the system. Good bye emul-linux-x86-* stuff which sometimes blcoking, messing system. Many thanks for the smart developers. After building everything on dual libs, android sdk, android studio and rom source went flawlessly