Fix Eval System tests.

[joaquinffernandez]

Currently disable pw_map and map eval system tests because they are failing consistently. Either fix or update them so we can add them back to the test-suite.

[Kalashnikovni]

Together with this error it was detected that some tests failed while working with SBGs with empty sets of edges, such as:

N = 10

V1 = N

matchSCCTS(
  V %= {[1:1:V1]};
  Vmap %= <<{[1:1:V1]} -> 0*x+1>>; 
  map1 %= <<>>;
  map2 %= <<>>;
  Emap %= <<>>;
, 1
)

[Kalashnikovni]

After fixing the previous issue in the SBGraph::copy operation that didn't handle empty SBGs, executing the above test resulted in SEGFAULT, thus a run with GDB indicated:

#2 0x000055555567456c in SBG::LIB::SBGTopSortSBG::LIB::OrdPWMDInter::calculate (this=this@entry=0x7fffffffa210) at sbg/sbg_algorithms.cpp:697

which again was due to lack of handling of SBGs with empty sets of vertices.