series-diff: tweak replacement of ignored text
series-diff: tweak replacement of ignored text

Sometimes the "@@" lines end without a function name.  In that case there is no
space after the second "@@".  Tweak the regular expression to cover that case,
checking for end-of-line as an alternative to the space.  For consistency,
anchor the regexes to the beginning of the line as well.

patchew-project/patchew,patchew-project/patchew,patchew-project/patchew,patchew-project/patchew