When configuring Qt statically with OpenSSL support on macOS,
configuring a user project would fail, because WrapOpenSSLHeaders could
not be found.
Configuration fails, because we don't record OPENSSL_ROOT_DIR anywhere,
and WrapOpenSSLHeaders is a required dependency of the OpenSSL plugin.
Make the WrapOpenSSLHeaders dependency optional like WrapVulkanHeaders
for QtGui.
Note that when Qt is statically configured with -openssl-linked on
macOS, configuration of user projects will still fail like described
above.
Pick-to: 6.4
Fixes: QTBUG-96283
Change-Id: I0893e18767387ea849c7e5661f5421b71e3f64ab
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
d754e43721