Generated projects no longer redefine modules shipped by module-map xcframeworks

For xcframeworks that ship a module.modulemap, the generated project no longer adds the xcframework slice’s Headers directory to HEADER_SEARCH_PATHS. Xcode’s ProcessXCFramework already extracts those headers (and the map) into $(BUILT_PRODUCTS_DIR)/include, so the previous behavior put a second copy of the same module on the search path and broke builds with error: redefinition of module 'X'. Xcframeworks without a module map (cached library products) keep their headers on the search path.