sorry for the delay - I went to work, and they actually made me work!
Anyway - below is a copy of my compile-litebar.sh
#!/bin/bash
export PATH=/mnt/mxe/usr/bin:$PATH
MXE_INCLUDE_PATH=/mnt/mxe/usr/i686-w64-mingw32.static/include
MXE_LIB_PATH=/mnt/mxe/usr/i686-w64-mingw32.static/lib
i686-w64-mingw32.static-qmake-qt4 \
BOOST_LIB_SUFFIX=-mt \
BOOST_THREAD_LIB_SUFFIX=_win32-mt \
BOOST_INCLUDE_PATH=$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=$MXE_LIB_PATH \
QMAKE_LRELEASE=/mnt/mxe/usr/i686-w64-mingw32.static/qt/bin/lrelease litebar-qt.pro
make -f Makefile.Release
I setup my build environment over a year ago and things are a little fuzzy ...
Please note that I use qt4 -not qt5 and I don't remember why ...
( I assume you installed QT)
Verify that your PATH env var contains the correct location for mxe
export PATH=/mnt/mxe/usr/bin:$PATH
I've forgotten to do the export PATH a few times and got that error, which is why I put it in the compile script
