Added functional solver dgesvx on magma (s,d,c,z) and tests for svx,msv and sv. To tests accuracy we compare results between the different methods. Some magma functions need to be adapted for Magma 4.1 or they will probably not work for Xeon Phi. The difference comes from the modification of type : cuDoubleComplex to magmaDoubleComplex to enable multi-support with Xeon Phi.