Make ALUGRID_DISABLE_METIS a proper CMake option
This MR changes the way METIS
is disabled inside of the dune-alugrid module. It simply disables finding it. This disabling is module-local and does not influence other downstream modules. Since this decision influences the dunealugrid library but is also local to alugrid, a new entry in the config.h
file is added to indicate this.
Details
The effect of setting variable ALUGRID_DISABLE_METIS
was before this MR that internally the HAVE_METIS
CMake varibale was unset. But HAVE_METIS
is not checked anymore after the the dune-common macros are parsed. It is not (and was never) meant to be a customization point for enabling or disabling METIS. The HAVE_METIS
CMake variable is actually set once and then considered a readonly property that modules can check but a modification has no effect at all.
An alternative to disabling that CMake searches for METIS is to not set the METIS flags to the dunealugrid library.