Rewrite depsolver to use a series of passes over all packages.

The big change is that we follow one step of the depedency chain for
each package to resolve in each iteration, and repeat until there are
no more possible moves. In contrast the old depsolver would try to
follow the dependency chain completely for one package at a time.

This new approach is simpler and faster, and at the same time more
roboust. Instead of knowing how one newly installed package may
affect other packages (obsoleting, pulling in new packages etc), the
new algorithm just looks at the total list of requires, provides,
obsoletes and conflicts after installing new packages.

 #ifndef _RAZOR_INTERNAL_H_

 #define _RAZOR_INTERNAL_H_

 #define ALIGN(value, base) (((value) + (base - 1)) & ~((base) - 1))

 /* Utility functions */

 int razor_create_dir(const char *root, const char *path);

 int razor_write(int fd, const void *data, size_t size);

 typedef int (*razor_compare_with_data_func_t)(const void *p1,

 					      const void *p,

 					      void *data);

 uint32_t *

 razor_qsort_with_data(void *base, size_t nelem, size_t size,

 		      razor_compare_with_data_func_t compare, void *data);

 #endif /* _RAZOR_INTERNAL_H_ */