fix: error while loading shared libraries (#296)

Add the linux-wallpaperengine library directory to the LD_LIBRARY_PATH

    The linker cannot find the required library because it is not located
    in the standard system paths. This results in the following error:

    ./linux-wallpaperengine: error while loading shared libraries:
    libkissfft-float.so.131: cannot open shared object file: No such
    file or directory

packaging/archlinux/PKGBUILD

@@ -44,8 +44,11 @@ package() {
     DESTDIR="$pkgdir" cmake --install build
     # create forwarding script
     install -d -m755 "${pkgdir}/usr/bin"
-    echo "#!/bin/bash" > ${pkgdir}/usr/bin/${_pkgname}
-    echo "cd /opt/${_pkgname}; ./linux-wallpaperengine \$*" >> ${pkgdir}/usr/bin/${_pkgname}
+    cat > "${pkgdir}/usr/bin/${_pkgname}" << EOF
+#!/bin/bash
+export LD_LIBRARY_PATH="/opt/${_pkgname}/lib:\$LD_LIBRARY_PATH"
+cd /opt/${_pkgname}; ./${_pkgname} "\$@"
+EOF
     chmod +x ${pkgdir}/usr/bin/${_pkgname}
     chmod +x ${pkgdir}/opt/${_pkgname}/linux-wallpaperengine
 }