Remove CTR_DRBG_STATE alignment marker.

We don't get up to 16-byte alignment without additional work like
https://boringssl-review.googlesource.com/20204. This just makes UBSan
unhappy at us.

Change-Id: I55d9cb5b40e5177c3c7aac7828c1d22f2bfda9a6
Reviewed-on: https://boringssl-review.googlesource.com/20464
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

crypto/fipsmodule/rand/internal.h

@@ -41,7 +41,7 @@ int rand_fork_unsafe_buffering_enabled(void);
 // CTR_DRBG_STATE contains the state of a CTR_DRBG based on AES-256. See SP
 // 800-90Ar1.
 typedef struct {
-  alignas(16) AES_KEY ks;
+  AES_KEY ks;
   block128_f block;
   ctr128_f ctr;
   union {