Fix test suite and benchmarks for the sparse routines

[ClementPernet]

The test files tests/test-sparse.C tests/test-fspmv-recint.C

are currently removed from the main test-suite as they segfault early on. This seems to be related to the ReadSmsFormat matrix reader. This issue is therefore related to #1 (new matrix reader and writer).

The related benchmarks are there benchmarks/benchmark-fspmm.C benchmarks/benchmark-fspmv.C and need a polish to fit within the standard benchmark framework.