-Wunknown-warning-option from arch/arm64/Makefile

[nathanchance]

https://lore.kernel.org/lkml/1559920965.6132.56.camel@lca.pw/

https://lore.kernel.org/linux-arm-kernel/20190607154010.GA41392@archlinux-epyc/

https://git.kernel.org/arm64/c/ebcc5928c5d925b1c8d968d9c89cdb0d0186db17

warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option] 
...
ld.lld: error: undefined symbol: __efistub___stack_chk_guard
>>> referenced by arm-stub.c:73 (/home/nathan/cbl/linux/drivers/firmware/efi/libstub/arm-stub.c:73)
>>>               arm-stub.stub.o:(__efistub_install_memreserve_table) in archive ./drivers/firmware/efi/libstub/lib.a

Patch sent: https://lore.kernel.org/lkml/20190607161201.73430-1-natechancellor@gmail.com/

arm64 -rc4 will be broken but Will said he would send it as a fix for -rc5.

[nathanchance]

Patch accepted: https://git.kernel.org/arm64/c/fa63da2ab046b885a7f70291aafc4e8ce015429b

[nathanchance]

Merged into mainline: https://git.kernel.org/torvalds/c/fa63da2ab046b885a7f70291aafc4e8ce015429b