make definition that should be static static

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@4676 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/srtp/crypto/rng/prng.c

@@ -47,7 +47,7 @@
 
 /* single, global prng structure */
 
-x917_prng_t x917_prng;
+static x917_prng_t x917_prng;
 
 err_status_t
 x917_prng_init(rand_source_func_t random_source) {