Coverity 1545176: dereference before NULL check

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
(Merged from #22211)

(cherry picked from commit 1541083)

crypto/rand/rand_lib.c

@@ -529,13 +529,14 @@ static EVP_RAND_CTX *rand_new_seed(OSSL_LIB_CTX *libctx)
     EVP_RAND *rand;
     RAND_GLOBAL *dgbl = rand_get_global(libctx);
     EVP_RAND_CTX *ctx = NULL;
-    const char *propq = dgbl->seed_propq;
+    const char *propq;
     char *name, *props = NULL;
     size_t props_len;
     OSSL_PROPERTY_LIST *pl1, *pl2, *pl3 = NULL;
 
     if (dgbl == NULL)
         return NULL;
+    propq = dgbl->seed_propq;
     if (dgbl->seed_name != NULL) {
         name = dgbl->seed_name;
     } else {