SerialIOTest: Cleanup ADIOS1/2

Just be more wide in what we cover by explictly excluding ADIOS1.

Author: ax3l

test/SerialIOTest.cpp

@@ -4154,8 +4154,9 @@ iterate_nonstreaming_series(
         Series writeSeries( file, Access::CREATE );
         if( variableBasedLayout )
         {
-            if( writeSeries.backend() != "ADIOS2" )
+            if( writeSeries.backend() == "ADIOS1" )
             {
+                // unsupported in ADIOS1
                 return;
             }
             writeSeries.setIterationEncoding(
@@ -4282,7 +4283,7 @@ extendDataset( std::string const & ext )
     std::iota( data2.begin(), data2.end(), 25 );
     {
         Series write( filename, Access::CREATE );
-        if( ext == "bp" && write.backend() != "ADIOS2" )
+        if( ext == "bp" && write.backend() == "ADIOS1" )
         {
             // dataset resizing unsupported in ADIOS1
             return;