Revert "Port cl_assert_equal_sz() from libgit2"

This reverts commit 96658871b84ff647e0da2bff22ec2de4a5e9b5f0.
Merge pull request #42 from nulltoken/ntk/fix/revert_cl_assert_equal_sz_def

Revert "Port cl_assert_equal_sz() from libgit2"