imports: Switch to Microsoft GSL implementation

... with two minor code base changes compared to previous
use of gsl-lite:

- dag.hpp: ActionNode::Ptr and ArtifactNode::Ptr are not
  wrapped in gsl::not_null<> anymore, due to lack of support
  for wrapping std::unique_ptr<>. More specifically, the
  move constructor is missing, rendering it impossible to
  use std::vector<>::emplace_back().

- utils/cpp/gsl.hpp: New header file added to implement the
  macros ExpectsAudit() and EnsureAudit(), asserts running
  only in debug builds, which were available in gsl-lite but
  are missing in MS GSL.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/utils/automata/dfa_minimizer.hpp b/src/utils/automata/dfa_minimizer.hpp
index 617617e3..ae647b44 100644
--- a/src/utils/automata/dfa_minimizer.hpp
+++ b/src/utils/automata/dfa_minimizer.hpp
@@ -111,7 +111,7 @@ class DFAMinimizer {
             it = buckets_.emplace(bucket_id, Bucket{std::move(symbols)}).first;
         }
         it->second.states.emplace(name, transitions);
-        gsl_Ensures(buckets_by_state_.emplace(name, bucket_id).second);
+        Ensures(buckets_by_state_.emplace(name, bucket_id).second);
     }
 
     // Compute bisimulation for each state and return a map, which maps a