patched matrix-sync validation test

Corrected dereference of wasGpuSynced, as discussed in #581

Author: otbrown

tests/unit/operations.cpp

@@ -987,7 +987,7 @@ void testOperationValidation(auto operation, bool multiplyOnly) {
 
         // only relevant to variable-size matrix functions
         if constexpr (Targs == any && (Args == compmatr || Args == diagmatr || Args == diagpower))
-            std::get<0>(furtherArgs).wasGpuSynced = 0;
+            *(std::get<0>(furtherArgs).wasGpuSynced) = 0;
         else
             return; // avoid empty test