Add Sieve support (RFC 5804) to s_client ("-starttls sieve")

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2300)
diff --git a/apps/apps.c b/apps/apps.c
index 969b6b8..216bc79 100644
--- a/apps/apps.c
+++ b/apps/apps.c
@@ -2664,3 +2664,11 @@
     }
     return 1;
 }
+
+void make_uppercase(char *string)
+{
+    int i;
+
+    for (i = 0; string[i] != '\0'; i++)
+        string[i] = toupper((unsigned char)string[i]);
+}