Initialize glob->user to NULL #899

Job	Run time
CMake Serial Minimal Build on Linux	1m 4s
CMake Serial With Clawpack Build on Linux	6m 42s
CMake Serial With Clawpack and HDF Build on Linux	7m 57s
CMake Serial With GeoClaw Build on Linux	1m 11s
CMake Serial With CudaClaw (CUDA 10.1) Build on Linux	2m 51s
CMake Serial With CudaClaw (CUDA 11.3) Build on Linux	3m 26s
CMake MPI Minimal Build on Linux	1m 47s
CMake MPI With Clawpack Build on Linux	7m 6s
CMake MPI With Clawpack and HDF Build on Linux	8m 19s
CMake MPI With GeoClaw Build on Linux	1m 56s
CMake build on MacOS	6m 4s
CMake MPI With CudaClaw (CUDA 10.1) Build on Linux	2m 56s
CMake MPI With CudaClaw (CUDA 11.3) Build on Linux	3m 53s
CMake MPI With ThunderEgg Build on Linux	3m 21s
	58m 33s

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