Allow config'n of incl of CertificateReq CA list Y/N at compile-time

Introduces MBEDTLS_SSL_CONF_CERT_REQ_CA_LIST which allows to configure
at compile-time whether a CA list should be included in the
CertificateRequest message sent by the server.

Impact on code-size:

|  | GCC 8.2.1 | ARMC5 5.06 | ARMC6 6.12 |
| --- | --- | --- | --- |
| `libmbedtls.a` before  | 23131 | 23805 | 26673 |
| `libmbedtls.a` after | 23099 | 23781 | 26639 |
| gain in Bytes | 32 | 24 | 34 |
diff --git a/programs/ssl/query_config.c b/programs/ssl/query_config.c
index 29b778c..bcdafb6 100644
--- a/programs/ssl/query_config.c
+++ b/programs/ssl/query_config.c
@@ -2610,6 +2610,14 @@
     }
 #endif /* MBEDTLS_SSL_CONF_ENDPOINT */
 
+#if defined(MBEDTLS_SSL_CONF_CERT_REQ_CA_LIST)
+    if( strcmp( "MBEDTLS_SSL_CONF_CERT_REQ_CA_LIST", config ) == 0 )
+    {
+        MACRO_EXPANSION_TO_STR( MBEDTLS_SSL_CONF_CERT_REQ_CA_LIST );
+        return( 0 );
+    }
+#endif /* MBEDTLS_SSL_CONF_CERT_REQ_CA_LIST */
+
 #if defined(MBEDTLS_SSL_CONF_HS_TIMEOUT_MIN)
     if( strcmp( "MBEDTLS_SSL_CONF_HS_TIMEOUT_MIN", config ) == 0 )
     {