Remove pre-emptive loading of cython modules

Author: wlach

pandas/__init__.py

@@ -21,18 +21,6 @@
 # numpy compat
 from pandas.compat import is_numpy_dev as _is_numpy_dev
 
-try:
-    from pandas._libs import hashtable as _hashtable, lib as _lib, tslib as _tslib
-except ImportError as err:  # pragma: no cover
-    module = err.name
-    raise ImportError(
-        f"C extension: {module} not built. If you want to import "
-        "pandas from the source directory, you may need to run "
-        "'python setup.py build_ext --force' to build the C extensions first."
-    ) from err
-else:
-    del _tslib, _lib, _hashtable
-
 from pandas._config import (
     get_option,
     set_option,