[Wien] Patch to fix ROTDEF error in lapw0 for Fd3m et al.

[Martin Kroeker]

We have recently encountered an unexpected problem with lapw0 returning
"ROTDEF error", claiming "symmetry operation not found" for equivalent
positions of an X,X,X site in spacegroup Fd-3m. (One simplified example
is attached to this message to allow reproducing the problem.)
As it appears, SRC_lapw0/rotdef.f takes turns applying the centering
operations to the calculated distance vector looking for a match - and
then undoes that operation before trying the next, instead of simply
copying back the original value. This demonstrably leads to rounding
errors that can exceed the hardcoded tolerance threshold of 1.5e-7

The attached patch avoids the problem by trivially saving x1 before
the cascade of tests for centered lattices, and restoring it after
each that did not lead to a successful exit from the loop.
-- 
Dr. Martin Kroeker            martin at ruby.chemie.uni-freiburg.de
c/o Prof.Dr. Caroline Roehr
Institut fuer Anorganische und Analytische Chemie der Universitaet Freiburg

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