Take Cryptographic API outside the XXX_ALT check

The cryptographic API should not be related to whether or not
there is alternative implementation. The API should be same for regular
implementation, and for alternative implementation, so it is defined
outside of the XXX_ALT precompilation check in the cryptographic API header

include/mbedtls/aes.h

@@ -59,14 +59,14 @@
 #define inline __inline
 #endif
 
-#if !defined(MBEDTLS_AES_ALT)
-// Regular implementation
-//
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#if !defined(MBEDTLS_AES_ALT)
+// Regular implementation
+//
+
 /**
  * \brief The AES context-type definition.
  */
@@ -85,6 +85,10 @@ typedef struct
 }
 mbedtls_aes_context;
 
+#else  /* MBEDTLS_AES_ALT */
+#include "aes_alt.h"
+#endif /* MBEDTLS_AES_ALT */
+
 /**
  * \brief          This function initializes the specified AES context.
  *
@@ -391,18 +395,6 @@ MBEDTLS_DEPRECATED void mbedtls_aes_decrypt( mbedtls_aes_context *ctx,
 #undef MBEDTLS_DEPRECATED
 #endif /* !MBEDTLS_DEPRECATED_REMOVED */
 
-#ifdef __cplusplus
-}
-#endif
-
-#else  /* MBEDTLS_AES_ALT */
-#include "aes_alt.h"
-#endif /* MBEDTLS_AES_ALT */
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /**
  * \brief          Checkup routine.
  *