Common kernel build errors

These are the hybris-boot build errors most commonly seen in the Halium community. If you have found and fixed a new error, please document the steps that you have taken to fix it.

Implicit declaration of ‘kvfree’

If you receive something similar to the following error:

../../../../../../kernel/[...]/[...]/security/apparmor/apparmorfs.c: In function 'aa_simple_write_to_buffer':
../../../../../../kernel/[...]/[...]/security/apparmor/apparmorfs.c:110:3: error: implicit declaration of function 'kvfree' [-Werror=implicit-function-declaration]

Apply the patch nick kvfree() from apparmor.