Hdf5 1 8 22 (#212)

* Restores maintainer mode in the autotools (#200)

Maintainer mode should be enabled in development branches.

Also adds helpful commenting.

Add bin/switch_maint_mode
Disable maintainer mode for release.
Fix incomplete merge for stub functions in H5Fdhdfs.c

* Update configure for Restores maintainer mode in the autotools (#200).

* Update MANIFEST for switch_maint_mode script.

Co-authored-by: Dana Robinson <43805+derobins@users.noreply.github.com>