Some platforms don't define ENOSYS - use ENXIO instead on these.

src/libsodium/crypto_aead/aes256gcm/aesni/aead_aes256gcm_aesni.c

@@ -22,6 +22,10 @@
 
 #include <immintrin.h>
 
+#ifndef ENOSYS
+# define ENOSYS ENXIO
+#endif
+
 #if defined(__INTEL_COMPILER) || defined(_bswap64)
 #elif defined(_MSC_VER)
 # define _bswap64(a) _byteswap_uint64(a)

src/libsodium/sodium/utils.c

@@ -23,6 +23,10 @@
 # include <unistd.h>
 #endif
 
+#ifndef ENOSYS
+# define ENOSYS ENXIO
+#endif
+
 #if defined(_WIN32) && (!defined(WINAPI_FAMILY) || WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP)
 # define WINAPI_DESKTOP
 #endif