Fix preprocessor macro existence check in bignum.c
@@ -741,14 +741,19 @@ static mbedtls_mpi_uint mpi_uint_bigendian_to_host( mbedtls_mpi_uint x )
#if ( __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ )
/* For GCC and Clang, have builtins for byte swapping. */
-#if( defined(__GNUC__) && defined(__GNUC_PREREQ) && __GNUC_PREREQ(4,3) )
+#if defined(__GNUC__) && defined(__GNUC_PREREQ)
+#if __GNUC_PREREQ(4,3)
#define have_bswap
-#elif defined(__clang__) && \
- defined(__has_builtin) && \
- __has_builtin(__builtin_bswap32) && \
+#endif
+#endif
+
+#if defined(__clang__) && defined(__has_builtin)
+#if __has_builtin(__builtin_bswap32) && \
__has_builtin(__builtin_bswap64)
#define have_bswap
#endif
+#endif
+
#if defined(have_bswap)
/* The compiler is hopefully able to statically evaluate this! */
switch( sizeof(mbedtls_mpi_uint) )
