ext/zip: Remove un-needed check for zip_open

[hughmcmaster]

Updated per review feedback and upstream changes.

[hughmcmaster]

@nikic, this is waiting for a review whenever you get time.

[nikic]

@hughmcmaster As said before, I'm not sure that removing those -L$LIBZIP_LIBDIR is correct and expect that it will fail for shared builds and we need to use $ZIP_SHARED_LIBADD there instead. Can you check whether --with-zip=shared works correctly after these changes?

[hughmcmaster]

This version removes the un-necessary zip_open symbol check and adds PHP_EVAL_LIBLINE to match all other pkg-config-based extensions. This means PHP_ADD_LIBRARY_WITH_PATH is no longer needed.

A future PR will replace $LIBZIP_LIBDIR with $LIBZIP_LIBS.

Thank you to everyone for your patience and explanations on the issues in the previous PR versions.