proxychains-ng should support both 32-bit and 64-bit binaries

Hello,

proxychains-ng does not play nice with different archs. When I try to run a 64-bit program, it works:

$ proxychains4 /usr/bin/fc-cat 2>&1 | grep proxy
[proxychains] config file found: /etc/proxychains.conf
[proxychains] preloading /usr/lib64/libproxychains4.so
[proxychains] DLL init: proxychains-ng 4.10

But this is what I get with 32-bit program:

$ proxychains4 /usr/bin/fc-cat32 2>&1 | grep proxy
[proxychains] config file found: /etc/proxychains.conf
[proxychains] preloading /usr/lib64/libproxychains4.so
ERROR: ld.so: object '/usr/lib64/libproxychains4.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.

It would be nice if proxychains-ng to not specify full path in its LD_PRELOAD. This would allow any 32-bit or 64-bit program to select its own version of libproxychains4.so. I extracted libproxychains4.so from a 32-bit compilation and installed it together with the full 64-bit proxychains-ng.

$ file /usr/bin/fc-cat32; LD_PRELOAD=libproxychains4.so /usr/bin/fc-cat32 2>&1 | grep proxy
/usr/bin/fc-cat32: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 3.0.0, BuildID[sha1]=bc52842b8a98bfc79fc36a63a1ac91554d5f2249, stripped
[proxychains] DLL init: proxychains-ng 4.10
$ file /usr/bin/fc-cat32; LD_PRELOAD=libproxychains4.so /usr/bin/fc-cat 2>&1 | grep proxy
/usr/bin/fc-cat32: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 3.0.0, BuildID[sha1]=bc52842b8a98bfc79fc36a63a1ac91554d5f2249, stripped
[proxychains] DLL init: proxychains-ng 4.10

Also, it would be nice to have a ./configure or Makefile argument that allows to compile 32-bit version of libproxychains4.so when compiling proxychains-ng for 64-bit. This would help packagers.

Start by tracing how proxychains4 sets LD_PRELOAD for the commands shown, then review the configure/Makefile options requested for producing a 32-bit library alongside a 64-bit build. Done means both 32-bit and 64-bit dynamically linked programs select a compatible proxychains library and packagers can request the additional 32-bit build.