arm64: enable bloating kernel with ext errors strings

Chase commit 8e8d3068dc ("amd64 GENERIC: enable bloating kernel with
ext errors strings") from amd64.  In general we would like to keep
GENERIC kernel options in sync between the Tier-1 architectures.

PR:		289236
Reviewed by:	andrew
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52342

sys/arm64/conf/std.arm64

@@ -7,6 +7,7 @@ makeoptions	WITH_CTF=1		# Run ctfconvert(1) for DTrace support
 options 	SCHED_ULE		# ULE scheduler
 options 	NUMA			# Non-Uniform Memory Architecture support
 options 	PREEMPTION		# Enable kernel thread preemption
+options 	BLOAT_KERNEL_WITH_EXTERR
 options 	VIMAGE			# Subsystem virtualization, e.g. VNET
 options 	INET			# InterNETworking
 options 	INET6			# IPv6 communications protocols