gitk: Rename 'tagcontents' to 'cached_tagcontent'
gitk: Rename 'tagcontents' to 'cached_tagcontent'

Name the 'tagcontents' variable similarly to the rest of the
variables cleared in the changedrefs() function.

This makes the naming consistent and provides a hint that it
should be cleared when reloading gitk's cache.

Suggested-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>
Signed-off-by: David Aguilar <9de348c050f7cd1ca590883733c4e531ce610bf4@gmail.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git