message: Fix cmake warning
diff: # - BENCHMARK_INCLUDE_DIRS
  include(MfemCmakeUtilities)
  -mfem_find_package(BENCHMARK BENCHMARK BENCHMARK_DIR
  +mfem_find_package(Benchmark BENCHMARK BENCHMARK_DIR
  "include" "benchmark/benchmark.h"
  "lib" "benchmark"
  "Paths to headers required by Google Benchmark."
  