Move git_sort(), a stable sort, into into libgit.a

2019-10-02T05:44:51Z

The `qsort()` function is not guaranteed to be stable, i.e. it does not promise to maintain the order of items it is told to consider equal. In contrast, the `git_sort()` function we carry in `compat/qsort.c` _is_ stable, by virtue of implementing a merge sort algorithm. In preparation for using a stable sort in Git's rename detection, move the stable sort into `libgit.a` so that it is compiled in unconditionally, and rename it to `git_stable_qsort()`. Note: this also makes the hack obsolete that was introduced in fe21c6b285d (mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8), 2018-10-30), where we included `compat/qsort.c` directly in `compat/mingw.c` to use the stable sort. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano

git/stable-qsort.c, branch v2.26.1

Move git_sort(), a stable sort, into into libgit.a