ci: use DC_SHA1=YesPlease on osx-clang job for CI

7b8cfe3 (Merge branch 'ed/fsmonitor-on-networked-macos',
2022-10-17) broke the build on macOS with sha1dc by bypassing our
hash abstraction (git_SHA_CTX etc.), but it wasn't caught before the
problematic topic was merged down to the 'master' branch.  Nobody
was even compile testing with DC_SHA1 set, although it is the
recommended choice in these days for folks when they use SHA-1.

This was because the default for macOS uses Apple Common Crypto, and
both of the two CI jobs did not override the default.  Tweak one of
them to use DC_SHA1 to improve the coverage.

We may want to give similar diversity for Linux jobs so that some of
them build with other implementations of SHA-1; they currently all
build and test with DC_SHA1 as that is the default on everywhere
other than macOS.

But let's start small to fill only the immediate need.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: gitster

ci/lib.sh

@@ -259,6 +259,8 @@ macos-latest)
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=$(which python3)"
 	else
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=$(which python2)"
+		MAKEFLAGS="$MAKEFLAGS NO_APPLE_COMMON_CRYPTO=NoThanks"
+		MAKEFLAGS="$MAKEFLAGS DC_SHA1=YesPlease NO_OPENSSL=NoThanks"
 	fi
 	;;
 esac