Define WINHTTP_NO_CLIENT_CERT_CONTEXT if needed

docs: stop mentioning libgit2's "master" branch

Co-authored-by: lhchavez <lhchavez@lhchavez.com>

The name of libgit2's main branch is now "main" but contributing.md and
release.md still reference "master" as the main branch.  Fix it.

Tolerate readlink size less than st_size

Patch documentation

In https://github.com/libgit2/libgit2/pull/5723/files/fc46dc06f52f854f74371682f911f13856c68edb#r540092847, I was confused by the semantics of `git_index_find`. The documentation says both that it returns the output value in `at_pos` and that it returns it directly as an `int`. This is incorrect; the return value is only returned via `at_pos`.

tests: clean up memory leak, fail on leak for win32

Fix issues with Proxy Authentication after httpclient refactor

Fix documentation formatting

Update README.md for additional Delphi bindings

Manually merging #5842

When a split src gets turned into a rename, it should
also lose the IS_RENAME_TARGET flag, so that it doesn't
get processed in a subsequent iteration as a rename target.
Doing so can cause an assertion failure because it no
longer has the SPLIT flag.

Fixes #5811.

buf: remove unnecessary buf_text namespace

filter: stop taking git_buf as user input