Merge branch 'jc/optional-path'

"git config get --path" segfaulted on an ":(optional)path" that
does not exist, which has been corrected.

* jc/optional-path:
  config: really treat missing optional path as not configured
  config: really pretend missing :(optional) value is not there
  config: mark otherwise unused function as file-scope static

diff --cc builtin/blame.c
Simple merge

diff --cc builtin/config.c
Simple merge

diff --cc builtin/receive-pack.c
Simple merge

diff --cc config.c
Simple merge

diff --cc fetch-pack.c
Simple merge

diff --cc fsck.c
Simple merge

diff --cc gpg-interface.c
Simple merge

diff --cc setup.c
Simple merge

diff --cc t/meson.build
Simple merge