copybit: Fix type conversion error for GCC 4.7

GCC 4.7 has stricter type conversion rules

Change-Id: I699cfe1ceafb5728fb8e6f34f7b1996d3c812e7e
pmemalloc: fix GCC 4.7 errors

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: Id5d7bc86780bd716b97257400e15793c29ff4dfb