MFC r331356 (by emaste@):

Share Linux errno table with libsysdecode.

MFC r331056:
Share a single bsd-linux errno table across MD consumers

Three copies of the linuxulator linux_sysvec.c contained identical
BSD to Linux errno translation tables, and future work to support other
architectures will also use the same table. Move the table to a common
file to be used by all. Make it 'const int' to place it in .rodata.

(Some existing Linux architectures use MD errno values, but x86 and Arm
share the generic set.)

This change should introduce no functional change; a followup will add
missing errno values.

MFC r331057:
linux_errno.c: add newer errno values

Also introduce a static assert to ensure the list is kept up to date.

MFC r331060:
Chase r331057 in libsysdecode erno table