New function block16_zero.

ChangeLog

+2022-02-18  Niels Möller  <nisse@lysator.liu.se>
+
+	* block-internal.h (block16_zero): New function.
+
 2022-02-17  Niels Möller  <nisse@lysator.liu.se>
 
 	* gcm.c: Require that GCM_TABLE_BITS == 8. Delete old code for

block-internal.h

@@ -42,6 +42,13 @@
 #include "nettle-types.h"
 #include "memxor.h"
 
+static inline void
+block16_zero (union nettle_block16 *r)
+{
+  static const union nettle_block16 zero_block;
+  *r = zero_block;
+}
+
 static inline void
 block16_xor (union nettle_block16 *r,
 	     const union nettle_block16 *x)