AC_CHECK_LIB(GL, main, [libgl=true], [libgl=false], [-L/usr/X11R6/lib -L/usr/X11R6/lib64 -lXt -lXext])
AC_CHECK_LIB(pthread, main, [pthread=true], [pthread=false])
AC_CHECK_LIB(GL, main, [libgl=true], [libgl=false], [-L/usr/X11R6/lib -L/usr/X11R6/lib64 -lXt -lXext])
AC_CHECK_LIB(pthread, main, [pthread=true], [pthread=false])