Fix build on 32bit architectures

It fails with errors like
| ../../xfce4-systemload-plugin-1.3.2/panel-plugin/network.cc:126:13: error: no matching function for call to 'read_netload_libgtop'
|   126 |         if (read_netload_libgtop (&bytes[1]) != 0)
|       |             ^~~~~~~~~~~~~~~~~~~~
| ../../xfce4-systemload-plugin-1.3.2/panel-plugin/network.cc:42:1: note: candidate function not viable: no known conversion from 'guint64 *' (aka 'unsigned long long *') to 'gulong *' (aka 'unsigne
d long *') for 1st argument
|    42 | read_netload_libgtop (gulong *bytes)
|       | ^                     ~~~~~~~~~~~~~

Upstream-Status: Pending
Signed-off-by: Khem Raj <raj.khem@gmail.com>

--- a/panel-plugin/network.cc
+++ b/panel-plugin/network.cc
@@ -118,6 +118,7 @@ read_netload_proc (gulong *bytes)
 gint
 read_netload (gulong *net, gulong *NTotal)
 {
+    gulong tbytes[2];
     static gulong bytes[2];
     static gint64 time[2];
 
@@ -123,10 +124,12 @@ read_netload (gulong *net, gulong *NTota
 
     time[1] = g_get_monotonic_time ();
 
-    if (read_netload_proc (&bytes[1]) != 0)
-        if (read_netload_libgtop (&bytes[1]) != 0)
+    if (read_netload_proc (&tbytes[1]) != 0)
+        if (read_netload_libgtop (&tbytes[1]) != 0)
             return -1;
 
+    bytes[0] = tbytes[0];
+    bytes[1] = tbytes[1];
     if (time[0] != 0 && G_LIKELY (time[1] > time[0]) && G_LIKELY (bytes[1] >= bytes[0]))
     {
         guint64 diff_bits = 8 * (bytes[1] - bytes[0]);
