I tried configuring a BusyBox install on a new Fedora system where I installed ncurses like so: "sudo dnf install ncurses-devel" and I got this error when running "make menuconfig":

 *** Unable to find the ncurses libraries or the
 *** required header files.
 *** 'make menuconfig' requires the ncurses libraries.
 *** 
 *** Install ncurses (ncurses-devel) and try again.
 *** 
make[2]: *** [/home/test/kdev/busybox-1.36.1/scripts/kconfig/lxdialog/Makefile:15: scripts/kconfig/lxdialog/dochecklxdialog] Error 1
make[1]: *** [/home/test/kdev/busybox-1.36.1/scripts/kconfig/Makefile:14: menuconfig] Error 2
make: *** [Makefile:444: menuconfig] Error 2

After investigating, I modified the file "check-lxdialog.sh" at line 50 in the check() function:

Before:

check() {
        $cc -x c - -o $tmp 2>/dev/null <<'EOF'
#include CURSES_LOC
main() {}
EOF
	if [ $? != 0 ]; then
	    echo " *** Unable to find the ncurses libraries or the"       1>&2
	    echo " *** required header files."                            1>&2
	    echo " *** 'make menuconfig' requires the ncurses libraries." 1>&2
	    echo " *** "                                                  1>&2
	    echo " *** Install ncurses (ncurses-devel) and try again."    1>&2
	    echo " *** "                                                  1>&2
	    exit 1
	fi
}


After:

check() {
        $cc -x c - -o $tmp 2>/dev/null <<'EOF'
#include CURSES_LOC
int main() {}
EOF
	if [ $? != 0 ]; then
	    echo " *** Unable to find the ncurses libraries or the"       1>&2
	    echo " *** required header files."                            1>&2
	    echo " *** 'make menuconfig' requires the ncurses libraries." 1>&2
	    echo " *** "                                                  1>&2
	    echo " *** Install ncurses (ncurses-devel) and try again."    1>&2
	    echo " *** "                                                  1>&2
	    exit 1
	fi
}

Making this modification caused the ncurses library to be found properly and I was able to run "make menuconfig" successfully.