[file-roller] meson: fix executable bit

[Paolo Bacchilega <paobac src gnome org>]

commit d267cc47fe789161291dd69347f53eba5c8d6a37
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Thu Feb 8 14:10:48 2018 -0500

    meson: fix executable bit
    
    https://bugzilla.gnome.org/show_bug.cgi?id=793313

 0 files changed, 0 insertions(+), 0 deletions(-)
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diff --git a/postinstall.py b/postinstall.py
old mode 100644
new mode 100755