Silence mbedtls

#1

With debug.level=0 and debug.level=-1, mbedtls still outputs the following line to stderr every time I open a TLS connection:
"SW ECDH curve 3"

My build is automatically setting MBEDTLS_ECP_ATCA=1 but I am not using an external ATCA chip.

I think it is happening in mbedtls/library/ecdh.c, in the following function definition:
mbedtls_ecdh_gen_public_2()

  /* HW unavailable, fall through to sw impl. */
  fprintf(stderr, "SW ECDH curve %d\n", ctx->grp.id);

I don’t have Cesanta’s source for mbedtls so I don’t know the exact line number.

In the latest Cesanta binary build for mbedtls, is this line using an inappropriately verbose level and can this be made less verbose in the next point release?