Allow compile-time configuration of DTLS badmac limit

Introduces MBEDTLS_SSL_CONF_BADMAC_LIMIT to fix the maximum
number of records with bad MAC tolerated in DTLS at compile-time.

Impact on code-size:

|  | GCC | ARMC5 | ARMC6 |
| --- | --- | --- | --- |
| `libmbedtls.a` before  | 23511 | 24049 | 27903 |
| `libmbedtls.a` after | 23487 | 24025 | 27885 |
| gain in Bytes | 24 | 24 | 18 |
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 6d71120..87c1d24 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -549,6 +549,9 @@
     check_cmdline_param_compat "anti_replay" \
                                "MBEDTLS_SSL_CONF_ANTI_REPLAY"
 
+    # DTLS bad MAC limit
+    check_cmdline_param_compat "badmac_limit" \
+                               "MBEDTLS_SSL_CONF_BADMAC_LIMIT"
 }
 
 # Usage: run_test name [-p proxy_cmd] srv_cmd cli_cmd cli_exit [option [...]]