Add genelpa warning if matrix is not positive definite (#6022) #337

Job	Run time
Build with GNU toolchain	8m 5s
Build with Intel toolchain	8m 0s
Build extra components with GNU toolchain	20m 28s
Build extra components with Intel toolchain	19m 28s
Build with CUDA support	16m 52s
Build without LCAO	5m 14s
Build without ELPA	7m 58s
Build without MPI	6m 13s
Build without LCAO and MPI	3m 54s
	1h 36m 12s

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