Add additional parameter to dsa_builtin_paramgen to output the generated

seed to: this doesn't introduce any binary compatibility issues as the
function is only used internally.

The seed output is needed for FIPS 140-2 algorithm testing: the functionality
used to be in DSA_generate_parameters_ex() but was removed in OpenSSL 1.0.0

crypto/dsa/dsa_locl.h

@@ -56,4 +56,5 @@
 
 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 	const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
+	unsigned char *seed_out,
 	int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);