Address overflows pointed out by Coverity

This patch series is part of my effort to bring Git for Windows' Coverity reports down to zero; Previous patch series have been merged in 347fe8a91b5 (Merge branch 'js/coverity-fixes', 2026-07-16), 0b75ef5168c (Merge branch 'js/coverity-fixes-null-safety', 2026-07-19), fcc8c931b53 (Merge branch 'js/coverity-unchecked-returns-fix', 2026-08-24) and 8bc9c7fcfd8 (Merge branch 'js/coverity-fixes', 2026-10-03).

Johannes Schindelin (5):
archive-tar: guard get_path_prefix against zero-length input
http: use size_t for byte position in fwrite_sha1_file
wrapper: reject insanely large byte counts when reading/writing
git-compat-util: add signed_mult_overflows and mult_overflows
macros
date: avoid overflow in approxidate relative-time multiplication

 archive-tar.c     |  2 ++
 date.c            | 26 +++++++++++++++++++++--
 git-compat-util.h | 54 +++++++++++++++++++++++++++++++++++++++++++++++
 http.c            |  2 +-
 wrapper.c         | 10 +++++++++
 5 files changed, 91 insertions(+), 3 deletions(-)

base-commit: 6de20f6092dcf9bdb1c8efe03db4b70c82b423dd
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2253%2Fdscho%2Fcoverity-fixes-overflow-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2253/dscho/coverity-fixes-overflow-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2253

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