rand: Also use /dev/urandom on OpenBSD as well

On older OpenBSD releases you especially should not have been
using /dev/random, nowdays due to changes all the device nodes
are actually all the same so either way this code can be simplified
to not special case OpenBSD in vlc_rand_init().
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
(manually cherry picked from 3fc4af48)

src/misc/rand.c

@@ -50,15 +50,10 @@ static uint8_t okey[BLOCK_SIZE], ikey[BLOCK_SIZE];
 
 static void vlc_rand_init (void)
 {
-#if defined (__OpenBSD__) || defined (__OpenBSD_kernel__)
-    static const char randfile[] = "/dev/random";
-#else
-    static const char randfile[] = "/dev/urandom";
-#endif
     uint8_t key[BLOCK_SIZE];
 
     /* Get non-predictible value as key for HMAC */
-    int fd = vlc_open (randfile, O_RDONLY);
+    int fd = vlc_open ("/dev/urandom", O_RDONLY);
     if (fd == -1)
         return; /* Uho! */