touch peakfile after closing a SndFileSource

libsndfile (can|may) update the headers at close, which can lead to the file being marked newer than the peakfile,
thus causing a rebuild of the peakfile at session (re)load.

Originally detected by Grygorii

1 files changed, 1 insertions, 0 deletions

diff --git a/libs/ardour/sndfilesource.cc b/libs/ardour/sndfilesource.cc
index 35fec82145..73361c33da 100644
--- a/libs/ardour/sndfilesource.cc
+++ b/libs/ardour/sndfilesource.cc
@@ -255,6 +255,7 @@ SndFileSource::close ()
 	if (_sndfile) {
 		sf_close (_sndfile);
 		_sndfile = 0;
+		file_closed ();
 	}
 }