Replace __attribute__((malloc)) with __attribute__((__malloc__)) in m…

…acros.h

Fix macro attribute conflict with cmocka
Fixes #20776

CLA: trivial

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from #20869)

(cherry picked from commit 0bf7e94)

include/openssl/macros.h

@@ -314,7 +314,7 @@
 
 # ifndef OSSL_CRYPTO_ALLOC
 #  if defined(__GNUC__)
-#   define OSSL_CRYPTO_ALLOC __attribute__((malloc))
+#   define OSSL_CRYPTO_ALLOC __attribute__((__malloc__))
 #  elif defined(_MSC_VER)
 #   define OSSL_CRYPTO_ALLOC __declspec(restrict)
 #  else