[klibc] mips64: remove __unused from __jmp_buf

This field is not needed. Probably it was copied straight from the
32-bit mips __jmp_buf.

Signed-off-by: James Cowgill <james.cowgill@mips.com>
Link: https://www.zytor.com/pipermail/klibc/2018-March/003984.html
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
diff --git a/usr/include/arch/mips64/klibc/archsetjmp.h b/usr/include/arch/mips64/klibc/archsetjmp.h
index c4587dc..bfca777 100644
--- a/usr/include/arch/mips64/klibc/archsetjmp.h
+++ b/usr/include/arch/mips64/klibc/archsetjmp.h
@@ -18,7 +18,6 @@
 	unsigned long __sp;
 	unsigned long __s8;
 	unsigned long __ra;
-	unsigned long __unused;
 } __attribute__ ((aligned(8)));
 
 typedef struct __jmp_buf jmp_buf[1];