'make menuconfig' requires the ncurses libraries.

wss@ubuntu:~/linux/tool/buildroot-2019.02.6$ make menuconfig
mkdir -p /home/wss/linux/tool/buildroot-2019.02.6/output/build/buildroot-config/lxdialog
PKG_CONFIG_PATH="" make CC="/usr/bin/gcc" HOSTCC="/usr/bin/gcc" \
    obj=/home/wss/linux/tool/buildroot-2019.02.6/output/build/buildroot-config -C support/kconfig -f Makefile.br mconf
 *** Unable to find the ncurses libraries or the
 *** required header files.
 *** 'make menuconfig' requires the ncurses libraries.
 *** 
 *** Install ncurses (ncurses-devel or libncurses-dev 
 *** depending on your distribution) and try again.
 *** 
Makefile:253: recipe for target '/home/wss/linux/tool/buildroot-2019.02.6/output/build/buildroot-config/dochecklxdialog' failed
make[2]: *** [/home/wss/linux/tool/buildroot-2019.02.6/output/build/buildroot-config/dochecklxdialog] Error 1
Makefile:925: recipe for target '/home/wss/linux/tool/buildroot-2019.02.6/output/build/buildroot-config/mconf' failed
make[1]: *** [/home/wss/linux/tool/buildroot-2019.02.6/output/build/buildroot-config/mconf] Error 2
Makefile:84: recipe for target '_all' failed
make: *** [_all] Error 2

根据提示，添加ncurses libraries就行

sudo apt-get install libncurses5-dev