Merge branch 'cl/regexec-macos-leak' into jch

A compatibility workaround has been introduced for macOS to address
a memory leak in the system regex engine when it encounters invalid
multibyte sequences.  The workaround segments the input buffer at
invalid byte boundaries and searches each valid segment separately
using regexec(), avoiding the leaking path.

* cl/regexec-macos-leak:
  SQUASH???
  regexec: work around macOS TRE leak on invalid UTF-8

diff --cc Makefile
Simple merge

diff --cc git-compat-util.h
Simple merge

diff --cc meson.build
Simple merge

diff --cc t/t7810-grep.sh
Simple merge