Cross compile enviromint-qt using mxe and mingw on 64-bit Ubuntu 16.04.

Install mxe dependencies:
sudo apt-get install p7zip-full 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 g++-multilib libc6-dev-i386

Clone mxe github repo:
cd /mnt
git clone https://github.com/mxe/mxe.git

Compile boost:
cd /mnt/mxe
make MXE_TARGETS="i686-w64-mingw32.static" boost

Compile qt5:
make MXE_TARGETS="i686-w64-mingw32.static" qttools

Compile berkeley db:
cd /mnt
wget http://download.oracle.com/berkeley-db/db-5.3.28.tar.gz
tar zxvf db-5.3.28.tar.gz
cd /mnt/db-5.3.28
touch compile-db.sh
chmod ugo+x compile-db.sh

Enter Contents of compile-db.sh using nano or other text editor:
------------------------------------------------------
#!/bin/bash
MXE_PATH=/mnt/mxe
sed -i "s/WinIoCtl.h/winioctl.h/g" src/dbinc/win_db.h
mkdir build_mxe
cd build_mxe

CC=$MXE_PATH/usr/bin/i686-w64-mingw32.static-gcc \
CXX=$MXE_PATH/usr/bin/i686-w64-mingw32.static-g++ \
../dist/configure \
	--disable-replication \
	--enable-mingw \
	--enable-cxx \
	--host x86 \
	--prefix=$MXE_PATH/usr/i686-w64-mingw32.static

make

make install
------------------------------------------------------

Compile:
./compile-db.sh

Compile miniupnpc:
cd /mnt
wget http://miniupnp.free.fr/files/miniupnpc-1.6.20120509.tar.gz
tar zxvf miniupnpc-1.6.20120509.tar.gz
cd /mnt/miniupnpc-1.6.20120509
touch compile-m.sh
chmod ugo+x compile-m.sh

Enter contents of compile-m.sh using nano or other text editor:
-----------------------------------------------
#!/bin/bash
MXE_PATH=/mnt/mxe

CC=$MXE_PATH/usr/bin/i686-w64-mingw32.static-gcc \
AR=$MXE_PATH/usr/bin/i686-w64-mingw32.static-ar \
CFLAGS="-DSTATICLIB -I$MXE_PATH/usr/i686-w64-mingw32.static/include" \
LDFLAGS="-L$MXE_PATH/usr/i686-w64-mingw32.static/lib" \
make libminiupnpc.a

mkdir $MXE_PATH/usr/i686-w64-mingw32.static/include/miniupnpc
cp *.h $MXE_PATH/usr/i686-w64-mingw32.static/include/miniupnpc
cp libminiupnpc.a $MXE_PATH/usr/i686-w64-mingw32.static/lib
------------------------------------------------------

Compile:
./compile-m.sh

Add mxe bins to PATH:
export PATH=/mnt/mxe/usr/bin:$PATH

Download and Compile Enviromint:
cd /mnt
git clone https://github.com/pacificao/enviromint.git
cd /mnt/enviromint
touch compile-env.sh
chmod ugo+x compile-env.sh

Enter contents of compile-env.sh using nano or other text editor:
--------------------------------------------------
#!/bin/bash
MXE_INCLUDE_PATH=/mnt/mxe/usr/i686-w64-mingw32.static/include
MXE_LIB_PATH=/mnt/mxe/usr/i686-w64-mingw32.static/lib

i686-w64-mingw32.static-qmake-qt5 \
	BOOST_LIB_SUFFIX=-mt \
	BOOST_THREAD_LIB_SUFFIX=_win32-mt \
	BOOST_INCLUDE_PATH=$MXE_INCLUDE_PATH/boost \
	BOOST_LIB_PATH=$MXE_LIB_PATH \
	OPENSSL_INCLUDE_PATH=$MXE_INCLUDE_PATH/openssl \
	OPENSSL_LIB_PATH=$MXE_LIB_PATH \
	BDB_INCLUDE_PATH=$MXE_INCLUDE_PATH \
	BDB_LIB_PATH=$MXE_LIB_PATH \
	MINIUPNPC_INCLUDE_PATH=$MXE_INCLUDE_PATH \
	MINIUPNPC_LIB_PATH=$MXE_LIB_PATH \
	QMAKE_LRELEASE=/mnt/mxe/usr/i686-w64-mingw32.static/qt5/bin/lrelease Enviromint-qt.pro

make -f Makefile.Release
---------------------------------------------------------

Compile Enviromint-qt
./compile-blk.sh

Ensure you have proper permissions or this will fail
Use sudo chmod 777 -R /mnt before compiling
Avoid using root or sudo when compiling

Find Enviromint-qt.exe at /mnt/enviromint/release