syncqt: Use /usr/bin/env perl not /usr/bin/perl

This is because on some systems, /usr/bin/perl is too old to
run syncqt. MSYS is one such system.

Change-Id: I3e1aa2db557cc3919618350775e7218ae05aa93f
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>