config.pl full: exclude MBEDTLS_ENTROPY_FORCE_SHA256

This is a variant toggle, not an extra feature, so it should be tested
separately.

We test most of the effect of MBEDTLS_ENTROPY_FORCE_SHA256 (namely,
using SHA-256 in the entropy module) when we test the library with the
SHA512 module disabled (which we do at least via depends-hashes.pl).
This commit removes testing of the MBEDTLS_ENTROPY_FORCE_SHA256 option
itself, which should be added separately.

scripts/config.py

@@ -168,6 +168,7 @@ def include_in_full(name):
             'MBEDTLS_DEPRECATED_REMOVED',
             'MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED',
             'MBEDTLS_ECP_RESTARTABLE',
+            'MBEDTLS_ENTROPY_FORCE_SHA256', # Variant toggle, tested separately
             'MBEDTLS_HAVE_SSE2',
             'MBEDTLS_MEMORY_BACKTRACE',
             'MBEDTLS_MEMORY_BUFFER_ALLOC_C',