What version of MinGW/gcc are you using?
Could you please try the following:
gcc -O0 -g -o $NWCHEM_TOP/bin/LINUX/depend.x $NWCHEM_TOP/src/config/makefile.h
cd /home/amnikitin/nwchem-6.5/src/nwpw/nwpwlib/pseudopotential/paw_atom
ls -l paw_my_constants.h
rm dependencies
make FC=gfortran DEPEND_CC=gcc