Minor changes to sha256.c includes to bring them in line with sha512.c

Signed-off-by: Tom Cosgrove <[email protected]>

library/sha256.c

@@ -49,8 +49,15 @@
       defined(MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY)
 #    include <arm_neon.h>
 #  endif
-#  if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT) && defined(__linux__)
-#    include <sys/auxv.h>
+#  if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT)
+#    if defined(__unix__)
+#      if defined(__linux__)
+         /* Our preferred method of detection is getauxval() */
+#        include <sys/auxv.h>
+#      endif
+       /* Use SIGILL on Unix, and fall back to it on Linux */
+#      include <signal.h>
+#    endif
 #  endif
 #elif defined(_M_ARM64)
 #  if defined(MBEDTLS_SHA256_USE_A64_CRYPTO_IF_PRESENT) || \