syslog-ng: enable http module based on zlib support in curl

syslog-ng: enable http module based on zlib support in curl

Since version 4.4.0, syslog-ng added compression to http() destination
using zlib from curl. [1] However, zlib is currently disabled in curl [2]
and it prevented syslog-ng to start.

This commit changes the configuration opinion to enable http module only if
zlib support is enabled for curl and as well it adds dependency for zlib (in that case).
If the zlib is disabled, then it disables http module, so syslog-ng can start
and thus zlib dependency is not required.

[1] https://gitlab.nic.cz/turris/os/packages/-/issues/932
[2] https://github.com/openwrt/packages/blob/93cbaacbfb13048ad378520a7afea7c9027dd1d6/net/curl/Config.in#L134
Fixes: 4dd49d7c3cd571107958154f1ed1ec8d8dba7464 ("syslog-ng: update to version 4.4.0")
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>