bug fix to MiB value reported in job summary

- perf_mbytes is a global used later in pdf generation, do not overwrite
  in stdio output parsing

ChangeLog

@@ -2,6 +2,11 @@
 Darshan Release Change Log
 --------------------------
 
+Darshan-3.1.7
+=============
+* bug fix to MiB reported in I/O performance estimate of
+  darshan-job-summary.pl when both posix and stdio access is present
+
 Darshan-3.1.6
 =============
 * bug fix for linker failures caused when linking external libraries

darshan-util/darshan-job-summary/bin/darshan-job-summary.pl.in

@@ -166,8 +166,8 @@ while($line = <PARSE_OUT>)
         {
             if($current_module eq "STDIO")
             {
-                ($junk, $perf_mbytes) = split(':', $line, 2);
-                $stdio_perf_mbytes = $perf_mbytes / 1024 / 1024;
+                ($junk, $stdio_perf_mbytes) = split(':', $line, 2);
+                $stdio_perf_mbytes = $stdio_perf_mbytes / 1024 / 1024;
                 $stdio_perf_mbytes = sprintf("%.1f", $stdio_perf_mbytes);
             }
             elsif($perf_mbytes == 0)