package/samba4: Fix uClibc build on 64bit platforms by including stdint.h

Fixes
http://autobuild.buildroot.net/results/fdd/fdd9bb5bea4488fc9e16746222051156224317a6/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>