Merge branch 'tb/precompose-prefix-too'

When commands are started from a subdirectory, they may have to
compare the path to the subdirectory (called prefix and found out
from $(pwd)) with the tracked paths.  On macOS, $(pwd) and
readdir() yield decomposed path, while the tracked paths are
usually normalized to the precomposed form, causing mismatch.  This
has been fixed by taking the same approach used to normalize the
command line arguments.

* tb/precompose-prefix-too:
  MacOS: precompose_argv_prefix()

diff --cc builtin/diff-files.c
Simple merge

diff --cc builtin/diff.c
Simple merge

diff --cc builtin/submodule--helper.c
Simple merge

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

diff --cc git.c
Simple merge

diff --cc t/t3910-mac-os-precompose.sh
Simple merge