apply: Remove the quick rejection test

In the next commit, we will make it possible for blank context lines to match beyond the end of the file. That means that a hunk with a preimage that has more lines than present in the file may be possible to successfully apply. Therefore, we must remove the quick rejection test in find_pos(). find_pos() will already work correctly without the quick rejection test, but that might not be obvious. Therefore, comment the test for handling out-of-range line numbers in find_pos() and cast the "line" variable to the same (unsigned) type as img->nr. What are performance implications of removing the quick rejection test? It can only help "git apply" to reject a patch faster. For example, if I have a file with one million lines and a patch that removes slightly more than 50 percent of the lines and try to apply that patch twice, the second attempt will fail slightly faster with the test than without (based on actual measurements). However, there is the pathological case of a patch with many more context lines than the default three, and applying that patch using "git apply -C1". Without the rejection test, the running time will be roughly proportional to the number of context lines times the size of the file. That could be handled by writing a more complicated rejection test (it would have to count the number of blanks at the end of the preimage), but I don't find that worth doing until there is a real-world use case that would benfit from it. It would be possible to keep the quick rejection test if --whitespace=fix is not given, but I don't like that from a testing point of view. Signed-off-by: Björn Gustavsson <bgustavsson@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>