This adds MBEDTLS_MD_SHA1 to the list of default hashes for TLS 1.2
handshake signatures. Although SHA-1 is weak, this option is turned on in
the default mbedtls configuration file, and allows better compatibility
with older servers. In particular it allows an stm32-mbedtls-based client
to connect to an axtls-based client (eg default unix port and esp8266).
Signed-off-by: Damien George <damien@micropython.org>
To use it a board should define MICROPY_PY_USSL=1 and MICROPY_SSL_MBEDTLS=1
at the Makefile level. With the provided configuration it adds about 64k
to the build.
