Enable -Wmissing-variable-declarations and
-Wincompatible-pointer-types-discards-qualifiers (the latter did not require
any code changes).

Reviewed-by: Rich Salz <rsalz@openssl.org>
diff --git a/apps/s_client.c b/apps/s_client.c
index 3eb495a..65e3bb8 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -395,7 +395,7 @@
 
 #endif
 
-char *srtp_profiles = NULL;
+static char *srtp_profiles = NULL;
 
 #ifndef OPENSSL_NO_NEXTPROTONEG
 /* This the context that we pass to next_proto_cb */