mail/thunderbird: drop patches in preparation for update

$ svn commit
Sending Mk/Uses/gecko.mk
Sending mail/thunderbird/Makefile
Sending mail/thunderbird/distinfo
Sending mail/thunderbird/files/patch-addon-search
Replacing mail/thunderbird/files/patch-bug1021761
Adding mail/thunderbird/files/patch-bug1144632
Deleting mail/thunderbird/files/patch-bug1186967
[...]
Transmitting file data ..........done
Committing transaction...
svn: E165001: Commit failed (details follow):
svn: E165001: Commit blocked by pre-commit hook (exit code 1) with output:
Do not replace a file. This can lose history. Path: "/head/mail/thunderbird/files/patch-bug702179"

Additional errors may compound and may not be accurate

Do not replace a file. This can lose history. Path: "/head/mail/thunderbird/files/patch-bug1021761"
Do not replace a file. This can lose history. Path: "/head/mail/thunderbird/files/patch-bug1288587"
Do not replace a file. This can lose history. Path: "/head/mail/thunderbird/files/patch-bug847568"
Do not replace a file. This can lose history. Path: "/head/mail/thunderbird/files/patch-env-api-keys"
[...]

Pointy hat to: portmgr (multi-steps are error prone)