There a couple of issues with the link flags specified in PGXS for OS X, which this commit works around: 1. `-undefined dynamic_lookup` is needed for the linker not to require that all symbols be resolved at link time. 2. -bundle_loader is needed to have the symbols in the `postgres` binary take precedence over symbols with the same name defined elsewhere during runtime resolution. In particular, a function named `hash_create` is also defined in libsystem_c.dylib, and that function was being called without -bundle_loader specified. Tested on OS X 10.10.2 with clang-600.0.56. Fixes #88. Fixes #90.
The tupleslot that is initialized for us for ExecForeignInsert, ExecForeignUpdate, ExecForeignDelete does not seem to fill the attisdropped attribute according to the catalog. We detect such a case by not initalizing any conversion info at all for such an attribute, and skipping such nulls conversion info.