aes: make the no-asm constant time code path not the default

After OMC and OTC discussions, the 95% performance loss resulting from
the constant time code was deemed excessive for something outside of
our security policy.

The option to use the constant time code exists as it was in OpenSSL 1.1.1.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from #17600)

CHANGES.md

@@ -90,6 +90,15 @@ breaking changes, and mappings for the large list of deprecated functions.
 
 [Migration guide]: https://github.com/openssl/openssl/tree/master/doc/man7/migration_guide.pod
 
+### Changes between 3.0.1 and 3.0.2 [xx XXX xxxx]
+
+ * Made the AES constant time code for no-asm configurations
+   optional due to the resulting 95% performance degradation.
+   The AES constant time code can be enabled, for no assembly
+   builds, with: ./config no-asm -DOPENSSL_AES_CONST_TIME
+
+   *Paul Dale*
+
 ### Changes between 3.0.0 and 3.0.1 [14 dec 2021]
 
  * Fixed invalid handling of X509_verify_cert() internal errors in libssl

crypto/aes/aes_core.c

@@ -50,7 +50,7 @@
 #include <openssl/aes.h>
 #include "aes_local.h"
 
-#if !defined(OPENSSL_NO_AES_CONST_TIME) && !defined(AES_ASM)
+#if defined(OPENSSL_AES_CONST_TIME) && !defined(AES_ASM)
 
 # if (defined(_WIN32) || defined(_WIN64)) && !defined(__MINGW32__)
 #  define U64(C) C##UI64