work around type issues in varags reduce function calls in Fortran

[Roland Haas]

The old reduction API has an interface that, in Fortran, takes varaible numbers of arguments in the CCTK_Reduce function, which is not supportable in Fortran which does not have this concept. Similarly the CCTK_ReduceLocalScalar subroutines take a Fortran array as argument which triggers errors in some Fortran compilers when called with differently typed scalars.

This affects the TestReduction thorn as well as EHFinder.

These pull requests address the type issue:

• https://bitbucket.org/einsteintoolkit/einsteinanalysis/pull-requests/13/ehfinder-explicitly-convert-void-pointers
• https://bitbucket.org/cactuscode/cactustest/pull-requests/3/testreduce-work-around-f77-compilers

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[Roland Haas]

Please review.

[Roland Haas]

Unless objected I will apply this commit after 2020-07-15

[Roland Haas]

EHFinder change approved by @Peter Diener .

Applied as git hash 3df424fa "EHFinder: explicitly convert void* pointers to addresses" of einsteinanalysis

Applied as git hash 02b4a50 "TestReduce: work around F77 compilers checking subroutine argument lists" of cactustest

Will backport.

[Roland Haas]

Backported to ET_2020_05 as git hash 57490aa5 "EHFinder: explicitly convert void* pointers to addresses" of einsteinanalysis

[Roland Haas]

Backported to ET_2020_05 as git hash 8c6fb23 "TestReduce: work around F77 compilers checking subroutine argument lists" of cactustest