Nice tutorial. Thanks!
There is a small mistake and think you should change this step:
Install mxe dependencies:
sudo apt-get install apt-get install autoconf automake autopoint bash bison bzip2 cmake flex gettext git g++ gperf intltool libffi-dev libtool libltdl-dev libssl-dev libxml-parser-perl make openssl patch perl pkg-config python ruby scons sed unzip wget xz-utils
To
sudo apt-get install autoconf automake autopoint bash bison bzip2 p7zip-full cmake flex gettext git g++ gperf intltool libffi-dev libtool libltdl-dev libssl-dev libxml-parser-perl make openssl patch perl pkg-config python ruby scons sed unzip wget xz-utils
The apt-get install is duplicated and it is missing 7-Zip.