Filter absorbed deps from install export sets

When static deps (rmm, rapids_logger) are absorbed into libcudf.so via
whole-archive, they are not installed separately. The export-set merging
loop was copying rmm-exports' install packages (including rapids_logger)
into cudf-exports, producing a find_dependency(rapids_logger) that would
fail for consumers of an installed standalone build.

Skip packages matching _absorbed_deps names when merging install-side
export set metadata.

Author: vyasr

cpp/CMakeLists.txt

@@ -1133,6 +1133,11 @@ if(BUILD_SHARED_LIBS)
         PROPERTY "GLOBAL_TARGETS"
       )
       foreach(_pkg IN LISTS _pkg_names)
+        # Skip packages that are themselves absorbed into libcudf — they won't be installed or
+        # findable at install time.
+        if(_mode STREQUAL "install" AND _pkg IN_LIST _absorbed_deps)
+          continue()
+        endif()
         rapids_export_package(${_mode} ${_pkg} cudf-exports GLOBAL_TARGETS ${_global_tgts})
       endforeach()
     endforeach()