cgfsng: fix real bug and fake libc realloc bug
cgfsng: fix real bug and fake libc realloc bug

read_file was using the wrong value for the string length.  Also,
realloc on i386 is wonky with small sizes - so use a batch size
to avoid small reallocs.

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>

hfuCN/lxc,federicobriata/lxc,hfuCN/lxc,akshaykarle/lxc,caglar10ur/lxc,aeris/lxc,thmo/lxc,QingweiPeterLan/cs188-lxc,LynxChaus/lxc,cjwatson/lxc,ysbnim/lxc,aeris/lxc,terceiro/lxc,ss1h2a3tw/lxc,LynxChaus/lxc,tych0/lxc,tych0/lxc,hallyn/lxc,hallyn/lxc,aeris/lxc,thmo/lxc,ysbnim/lxc,QingweiPeterLan/cs188-lxc,ss1h2a3tw/lxc,caglar10ur/lxc,terceiro/lxc,ysbnim/lxc,QingweiPeterLan/cs188-lxc,federicobriata/lxc,cjwatson/lxc,terceiro/lxc,ss1h2a3tw/lxc,federicobriata/lxc,thmo/lxc,LynxChaus/lxc,tych0/lxc,akshaykarle/lxc,cjwatson/lxc,GreatFruitOmsk/lxc,GreatFruitOmsk/lxc,caglar10ur/lxc,akshaykarle/lxc,GreatFruitOmsk/lxc,hfuCN/lxc,hallyn/lxc