Patch libsodium randbytes

recipes/libsodium/random.patch

+--- a/src/libsodium/randombytes/sysrandom/randombytes_sysrandom.c	2018-06-03 07:26:17.413729023 +0200
++++ b/src/libsodium/randombytes/sysrandom/randombytes_sysrandom.c	2018-06-03 07:41:40.119390067 +0200
+@@ -162,10 +162,7 @@
+ /* LCOV_EXCL_START */
+     struct stat        st;
+     static const char *devices[] = {
+-# ifndef USE_BLOCKING_RANDOM
+-        "/dev/urandom",
+-# endif
+-        "/dev/random", NULL
++        "rand:", NULL
+     };
+     const char       **device = devices;
+     int                fd;