MFH: r531622 r531627 r531715

devel/git: Update to 2.26.0

Sponsored by: Rubicon Communications, LLC (Netgate)

devel/git: Fix build

I've committed the wrong changes in r531622 breaking git build. Fix it now.

Reported by: mandree and jbeich
Sponsored by: Rubicon Communications, LLC (Netgate)

devel/git: Update to 2.26.1

Security: CVE-2020-5260
Sponsored by: Rubicon Communications, LLC (Netgate)

Approved by: ports-secteam (joneum)