Fix test/evp_extra_test.c
Fix test/evp_extra_test.c

Because EVP_PKEY_CTX_new_from_name() could return a non-NULL context
with no value in it, the lack of legacy implementation when OpenSSL
was configured with 'no-ec' went through undetected.  This adds the
necessary guards to skip a test of SM2 in that case.

Reviewed-by: Paul Yang <184f6de988fc88cc661c91bad2c53ca35ab2d101@antfin.com>
(Merged from https://github.com/openssl/openssl/pull/12785)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl