Made supported curves configurable
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 53557f8..366277d 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -200,16 +200,29 @@
 
     SSL_DEBUG_MSG( 3, ( "client hello, adding supported_elliptic_curves extension" ) );
 
+#if defined(POLARSSL_ECP_DP_SECP521R1_ENABLED)
     elliptic_curve_list[elliptic_curve_len++] = 0x00;
     elliptic_curve_list[elliptic_curve_len++] = POLARSSL_ECP_DP_SECP521R1;
+#endif
+#if defined(POLARSSL_ECP_DP_SECP384R1_ENABLED)
     elliptic_curve_list[elliptic_curve_len++] = 0x00;
     elliptic_curve_list[elliptic_curve_len++] = POLARSSL_ECP_DP_SECP384R1;
+#endif
+#if defined(POLARSSL_ECP_DP_SECP256R1_ENABLED)
     elliptic_curve_list[elliptic_curve_len++] = 0x00;
     elliptic_curve_list[elliptic_curve_len++] = POLARSSL_ECP_DP_SECP256R1;
+#endif
+#if defined(POLARSSL_ECP_DP_SECP224R1_ENABLED)
     elliptic_curve_list[elliptic_curve_len++] = 0x00;
     elliptic_curve_list[elliptic_curve_len++] = POLARSSL_ECP_DP_SECP224R1;
+#endif
+#if defined(POLARSSL_ECP_DP_SECP192R1_ENABLED)
     elliptic_curve_list[elliptic_curve_len++] = 0x00;
     elliptic_curve_list[elliptic_curve_len++] = POLARSSL_ECP_DP_SECP192R1;
+#endif
+
+    if( elliptic_curve_len == 0 )
+        return;
 
     *p++ = (unsigned char)( ( TLS_EXT_SUPPORTED_ELLIPTIC_CURVES >> 8 ) & 0xFF );
     *p++ = (unsigned char)( ( TLS_EXT_SUPPORTED_ELLIPTIC_CURVES      ) & 0xFF );