Don't use typeof

Don't use typeof

clang complains with the xorg-macros warning flags:
src/context.c:58:36: error: extension used [-Werror,-pedantic,-Wlanguage-extension-token]
                                   typeof(new_paths));

This was not entirely correct, too. So bring back the casts to the
results of the allocation macros; might as well make them a bit more
type safe.

Signed-off-by: Ran Benita <ran234@gmail.com>