c++: fix comparison between signed and unsigned types

comparing int i with size_t size generates a sign-compare warning.
This commit solves the issue by giving i the type needed.
As older c standards do not allow to declare i after stack += 4 I
inserted the variable checked_stack that gets the type we need in the
comparison.

Signed-off-by: Alexander Polleti <metapsycholo@gmail.com>
1 file changed