6958257: Add support for alpha
Summary: Allow the Zero port to be built on alpha architectures
Reviewed-by: ohair
## copy/paste of MS950.b2c-irreversible## removed the entries of MS950.c2b-irreversible etries, this .nr# table only includes "b->c only" entries# (we don't need a MS950.c2b, the entries of MS950.c2b-irreversible# are added in MS950.b2c already)#0xF9FA 0x256D 0xF9FB 0x256E0xF9FC 0x25700xF9FD 0x256F0xA2CC 0x53410xA2CE 0x53450xF9F9 0x25500xF9E9 0x255E0xF9EA 0x256A0xF9EB 0x2561