[cmake] Adapt FindMETIS.cmake such that it also finds libscotchmetis

We now check for METIS_PartGraphKway, which is a symbol that we are actually
using and which is also in the implementation of scotch (see FS#1370)

cmake/modules/FindMETIS.cmake

@@ -52,7 +52,7 @@ if(METIS_LIBRARY)
   list(APPEND CMAKE_REQUIRED_LIBRARIES ${METIS_LIBRARIY})
   set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} ${METIS_LIBRARY})
   include(CheckSymbolExists)
-  check_function_exists(METIS_PartMeshDual HAVE_METIS_PARTMESH_DUAL)
+  check_function_exists(METIS_PartGraphKway HAVE_METIS_PARTGRAPHKWAY)
 endif(METIS_LIBRARY)
 
 # behave like a CMake module is supposed to behave
@@ -62,7 +62,7 @@ find_package_handle_standard_args(
   DEFAULT_MSG
   METIS_INCLUDE_DIR
   METIS_LIBRARY
-  HAVE_METIS_PARTMESH_DUAL
+  HAVE_METIS_PARTGRAPHKWAY
 )
 
 cmake_pop_check_state()
@@ -91,4 +91,4 @@ if(METIS_FOUND)
   foreach(dir ${METIS_INCLUDE_DIRS})
     set_property(GLOBAL APPEND PROPERTY ALL_PKG_FLAGS "-I${dir}")
   endforeach()
-endif()
\ No newline at end of file
+endif()