Add Nintendo Switch port.

Contributed by Swyter and vdweller84.

src/lj_prng.c

@@ -87,6 +87,10 @@ extern int sys_get_random_number(void *buf, uint64_t len);
 
 extern int sceRandomGetRandomNumber(void *buf, size_t len);
 
+#elif LJ_TARGET_NX
+
+#include <unistd.h>
+
 #elif LJ_TARGET_WINDOWS || LJ_TARGET_XBOXONE
 
 #define WIN32_LEAN_AND_MEAN
@@ -176,6 +180,11 @@ int LJ_FASTCALL lj_prng_seed_secure(PRNGState *rs)
   if (sceRandomGetRandomNumber(rs->u, sizeof(rs->u)) == 0)
     goto ok;
 
+#elif LJ_TARGET_NX
+
+  if (getentropy(rs->u, sizeof(rs->u)) == 0)
+    goto ok;
+
 #elif LJ_TARGET_UWP || LJ_TARGET_XBOXONE
 
   if (BCryptGenRandom(NULL, (PUCHAR)(rs->u), (ULONG)sizeof(rs->u),