[test-suite] Avoid segfault in CLAMR test on non-Linux systems

[dim]

Summary

On FreeBSD, the CLAMR test immediately segfaults on startup, when it
parses /proc/pid/status in the memstats_memused() function. This is
because the parser is not very robust, and the FreeBSD /proc format is
different than Linux.

I expect this code to crash on anything else than Linux, but for our
test purposes the memory statistics printed are not important, since
nobody ever looks at the produced output.

Since there is already a MEMORY define controlling the printing of
memory statistics, only call the memstats_memused() function if it is
explicitly enabled (which it is not, by default).

[brad]

BTW, there is some whitespace on 629.

MultiSource/Benchmarks/DOE-ProxyApps-C++/CLAMR/clamr_cpuonly.cpp

if(upper_mass_diff_percentage < 0){
       //printf("Setting sum mass error to %16.8lg\n",upper_mass_diff_percentage);
    }
 
    double cpu_time_main_setup = cpu_timer_stop(tstart_setup);
    #ifdef TIMING
    mesh->parallel_output("CPU:  setup time               time was",cpu_time_main_setup, 0, "s");
    #endif 
 
-   long long mem_used = memstats_memused();
    #ifdef MEMORY
+   long long mem_used = memstats_memused();
    if (mem_used > 0) {
       mesh->parallel_output("Memory used      in startup ",mem_used, 0, "kB");
       mesh->parallel_output("Memory peak      in startup ",memstats_mempeak(), 0, "kB");
       mesh->parallel_output("Memory free      at startup ",memstats_memfree(), 0, "kB");
       mesh->parallel_output("Memory available at startup ",memstats_memtotal(), 0, "kB");
    }
    #endif
 
#endif
          next_graphics_cycle += graphic_outputInterval;
 
          cpu_time_graphics += cpu_timer_stop(tstart_cpu);
       }
 
       //  Get overall program timing.
       double elapsed_time = cpu_timer_stop(tstart);
       
-      long long mem_used = memstats_memused();
       #ifdef MEMORY
+      long long mem_used = memstats_memused();
       if (mem_used > 0) {
          printf("Memory used      %lld kB\n",mem_used);
          printf("Memory peak      %lld kB\n",memstats_mempeak());
          printf("Memory free      %lld kB\n",memstats_memfree());
          printf("Memory available %lld kB\n",memstats_memtotal());
       }
       #endif
       state->output_timing_info(do_cpu_calc, do_gpu_calc, elapsed_time);