Fix exported interface include dir

[dg0yt]

include/zzip contains a header named stdint.h. This headers hides the compiler's stdint.h when a consumer links to the exported target, resulting in errors such as (cf. x64-linux in https://dev.azure.com/vcpkg/public/_build/results?buildId=78568):

error: '::int8_t' has not been declared

and (cf. x64-windows in https://dev.azure.com/vcpkg/public/_build/results?buildId=78568)

...\cstdint(31): error C2039: 'int_least8_t': is not a member of '`global namespace''
...\cstdint(31): error C2873: 'int_least8_t': symbol cannot be used in a using-d

According to the test file, the canonical pattern is #include <zzip/zzip.h>.

[dg0yt]

Merged but not in master and not in yesterday's release? Do you plan to release another patch release very soon, before people get used to the wrong pattern?
Updating zziplib is blocked now by stdint.h again, and without feedback, I don't know which patch to apply.
microsoft/vcpkg#37043

[dg0yt]

@gdraheim Do you need more information? I would be glad to have an early indication of how you plan to proceed. Changing the include directory here after package maintainers adopted individual fixes is a waste of resources.