Improve #12920 fix

[genotrance]

After #12779, nimgrep skipped newline after printing last match of each filename if --filenames. Original fix in #12920 was in the wrong spot and only addressed issue if a single match. This is a better solution since it covers any number of matches.

This needs to be backported to 1.2.0, is working correctly in 1.0.6 since #12779 wasn't ported there.

Before:

PS C:\Users\IEUser\Desktop\DL\programming\nimbass> nimgrep --filenames --recursive --oneline ".*[\\/](lib)?bass_fx[_-]?(static)?[0-9.\-]*\.dll$" C:\Users\IEUser\nimcache\nimterop\nimbassfx
C:\Users\IEUser\nimcache\nimterop\nimbassfx\bass_fx.dll:1: C:\Users\IEUser\nimcache\nimterop\nimbassfx\bass_fx.dllC:\Users\IEUser\nimcache\nimterop\nimbassfx\x64\bass_fx.dll:1: C:\Users\IEUser\nimcache\nimterop\nimbassfx\x64\bass_fx.dll2 matches

After:

> nimgrep --filenames --recursive --oneline ".*[\\/](lib)?bass_fx[_-]?(static)?[0-9.\-]*\.dll$" C:\Users\IEUser\nimcache\nimterop\nimbassfx
C:\Users\IEUser\nimcache\nimterop\nimbassfx\bass_fx.dll:1: C:\Users\IEUser\nimcache\nimterop\nimbassfx\bass_fx.dll
C:\Users\IEUser\nimcache\nimterop\nimbassfx\x64\bass_fx.dll:1: C:\Users\IEUser\nimcache\nimterop\nimbassfx\x64\bass_fx.dll
2 matches

[Araq]

Irrelevant CI failure, merging.

[genotrance]

@narimiran - needs to be backported to 1.2.0.

[narimiran]

@narimiran - needs to be backported to 1.2.0.

Thanks for the ping! Backported.