RPCS3 + Ubuntu

This weekend i had some time to play around with a emulator ( RPCS3)  on my Ubuntu box.
After installing bison and libedit-dev and fiddling around with LD_LIBRARY_PATH i got it to build

What i don't understand is why i had to do"export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/x86_64-linux-gnu/" considering on "/etc/ld.so.conf.d/"   when there was already a conf file with that path. Permissions issue perhaps? Can someone with more Ubuntu experience shed some light?
Now to the fun part of fidding with Asmjit and LLVM.