Build system: fix workaround for 64-bit integers in Fortran code

m4/ax_mexopts.m4

@@ -45,7 +45,6 @@ case ${MATLAB_ARCH} in
     else # glnxa64
       MATLAB_CFLAGS="$MATLAB_CFLAGS -fno-omit-frame-pointer"
       MATLAB_CXXFLAGS="$MATLAB_CXXFLAGS -fno-omit-frame-pointer"
-      MATLAB_FFLAGS="$MATLAB_FFLAGS -fdefault-integer-8"
     fi
     ax_mexopts_ok="yes"
     ;;
@@ -85,6 +84,11 @@ case ${MATLAB_ARCH} in
     ;;
 esac
 
+# Starting from MATLAB 7.8, on 64-bit platforms, BLAS and LAPACK expect 64-bit integers, so make it the default for integers in Fortran code
+if test "${MATLAB_ARCH}" = "glnxa64" -o "${MATLAB_ARCH}" = "win64" -o "${MATLAB_ARCH}" = "maci64"; then
+  AX_COMPARE_VERSION([$MATLAB_VERSION], [ge], [7.8], [MATLAB_FFLAGS="$MATLAB_FFLAGS -fdefault-integer-8"])
+fi
+
 # Converts the MATLAB version number into comparable integers with only major and minor version numbers
 # For example, 7.4.2 will become 0704
 ax_matlab_ver=`echo "$MATLAB_VERSION" | $SED -e 's/\([[0-9]]*\)\.\([[0-9]]*\).*/Z\1ZZ\2Z/' \