Added 'vm_swap' variable nullifying.

Thanks to KOSAKI Motohiro.

Bug-Redhat: https://bugzilla.redhat.com/show_bug.cgi?id=532668

proc/readproc.c

@@ -176,6 +176,7 @@ ENTER(0x220);
     P->vm_stack= 0;
     P->vm_exe  = 0;
     P->vm_lib  = 0;
+    P->vm_swap = 0;
     P->nlwp    = 0;
     P->signal[0] = '\0';  // so we can detect it as missing for very old kernels