Merge branch 'x86_ghash' into 'master'

Use Test instruction instead of And to check remaining single block

See merge request nettle/nettle!59

x86_64/pclmul/ghash-update.asm

@@ -141,7 +141,7 @@ PROLOGUE(_nettle_ghash_update)
 	jnz		.Loop
 
 .L1_block:
-	and		$1, BLOCKS
+	test		$1, BLOCKS
 	jz		.Ldone
 
 	movups		(DATA), M