Error while building legato 18.04.0 for WP7502 - fatal error: unistd.h: No such file or directory

Legato Application Framework
6

I added path and set toolchain but both y22-ext-wp750x and y17-ext are same soft link to y22-ext_SWI9X07Y_02.14.04.00

root@testUser:/opt/swi# ls
y17-ext
y22-ext_SWI9X07Y_02.14.04.00
y22-ext-wp750x

and it worked somehow

This time I used mangOH SDK but it first compile legato and then generate update to use.
I could update board to 18.04 legato version