maint: avoid gitlog-to-changelog diagnostic about unused entries

maint: avoid gitlog-to-changelog diagnostic about unused entries

* build-aux/git-log-fix: Comment out two unused entries.
Each of those two entries does indicate an error in a commit log,
but precedes the cut-off date, so has an actual VC'd ChangeLog entry.
I.e., gitlog-to-changelog generates ChangeLog entries since 2008-02,
and these two predate that.
* ChangeLog-2008: Make the indicated correction.