[SSSD] [sssd PR#1016][comment] proxy: set pwfield to x for files library

[pbrezina]

URL: https://github.com/SSSD/sssd/pull/1016
Title: #1016: proxy: set pwfield to x for files library

pbrezina commented:
"""
I switched to `strcasecmp`. I checkd the other cases were `is_files_provider` was used but those special cases should be really used only for a files provider. It is special in the way that it is enabled implicitly and it needs to really return what is in files. Proxy provider can be enabled only explicitly so we can rely on its configuration.
"""

See the full comment at https://github.com/SSSD/sssd/pull/1016#issuecomment-608373363