ElfDynLib: resolve lib from system paths

[Cloudef]

Implements the base that should usually work that is

• Check LD_LIBRARY_PATH if the binary is no setuid setgid binary
• Check /lib, /usr/lib, in that order

The missing parts are:

• DT_RPATH and DT_RUNPATH handling from the calling executable
• Reading /etc/ld.so.cache

For more details check man page of dlopen(3)

[Cloudef]

Is the x86_64-macos build bugged? Edit: seems like it unbugged itself

[Cloudef]

Updated for BYOS changed Edit: seems like x86_64-linux-release bugged