[rocprofv3] Fix calculation of services which collected data (#265)

Co-authored-by: Jonathan R. Madsen <jonathanrmadsen@gmail.com>

source/lib/rocprofiler-sdk-tool/tool.cpp

@@ -1643,12 +1643,14 @@ generate_output(tool::buffered_output<Tp, DomainT>& output_v,
 {
     if(!output_v) return;
 
-    // if it has reached this point, the generator is not empty
-    num_output_v += 1;
-
     // opens temporary file and sets read position to beginning
     output_v.read();
 
+    if(output_v.get_generator().empty()) return;
+
+    // if it has reached this point, the generator is not empty
+    num_output_v += 1;
+
     if(tool::get_config().stats || tool::get_config().summary_output)
     {
         output_v.stats =