The dh(g) parameter was read from param->beg instead of from the
cursor p returned by parsing dh(p). This caused dh(g) to always
report the same value as dh(p) when inspecting DH certificates
via CURLOPT_CERTINFO on non-OpenSSL backends.
The DSA branch correctly advances the cursor; the DH branch lost
this during what appears to be a copy-paste.
Add unit1676 to verify that dh(p) and dh(g) report distinct values
using a hand-crafted minimal DER certificate.
Assisted by: Claude Opus 4.6
Signed-off-by: Sergio Correia <scorreia@redhat.com>
Closes#21595
