Packaging for Debian

I've created a Debian package for retdec. It eventually runs this command to configure the sources:

cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=None -DCMAKE_INSTALL_SYSCONFDIR=/etc -DCMAKE_INSTALL_LOCALSTATEDIR=/var -DCMAKE_EXPORT_NO_PACKAGE_REGISTRY=ON -DCMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY=ON -DCMAKE_INSTALL_RUNSTATEDIR=/run "-GUnix Makefiles" -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_AUTOGEN_VERBOSE=ON -DCMAKE_INSTALL_LIBDIR=lib/x86_64-linux-gnu ..

At some point late in the build fails with exit code 2. The failure appears to be related to yaramod's installation directory not matching the one selected by the main configuration command. I played around with deps/yaramod/CMakeLists.txt a bit, passing in -DCMAKE_INSTALL_LIBDIR=lib/x86_64-linux-gnu to ExternalProject_Add, and got a bit further, but there still appear to be problems. Without the ability to specify an alternate install libdir, debian's multilib support won't work.

Start with deps/yaramod/CMakeLists.txt and reproduce the Debian build using the reported CMake configuration. Trace how CMAKE_INSTALL_LIBDIR is passed to yaramod and verify that its installation directory matches the main build; done means the build succeeds with Debian's alternate library directory and multilib layout.

Written by the indexing model from the issue text.