Don't free a NULL. Coverity ID 112.

apps/ocsp.c

diff --git a/apps/ocsp.c b/apps/ocsp.c
index 6b7e85d..23c7686 100644
--- a/apps/ocsp.c
+++ b/apps/ocsp.c
@@ -1337,8 +1337,8 @@
 			
 		}
 	err:
-
-	OCSP_REQ_CTX_free(ctx);
+	if (ctx)
+		OCSP_REQ_CTX_free(ctx);
 
 	return rsp;
 	}