ci/lib.sh: update a comment about installed P4 and Git-LFS versions

A comment in 'ci/lib.sh' claims that the "OS X build installs the
latest available versions" of P4 and Git-LFS, but since f2f4715
("ci: don't update Homebrew", 2019-07-03) that's no longer the case,
as it will install the versions which were recorded in the image's
Homebrew database when the image was created.

Update this comment accordingly.

Signed-off-by: SZEDER Gábor <[email protected]>
Acked-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: szeder

ci/lib.sh

@@ -163,8 +163,10 @@ linux-clang|linux-gcc)
 	export GIT_TEST_HTTPD=YesPlease
 
 	# The Linux build installs the defined dependency versions below.
-	# The OS X build installs the latest available versions. Keep that
-	# in mind when you encounter a broken OS X build!
+	# The OS X build installs much more recent versions, whichever
+	# were recorded in the Homebrew database upon creating the OS X
+	# image.
+	# Keep that in mind when you encounter a broken OS X build!
 	export LINUX_P4_VERSION="16.2"
 	export LINUX_GIT_LFS_VERSION="1.5.2"