Change assorted places in our Perl code that did things like
	system("prog $path/file");
to do it more like
	system('prog', "$path/file");
which is safe against spaces and other special characters in the path
variable.  The latter was already the prevailing style, but a few bits
of code hadn't gotten this memo.  Back-patch to 9.4 as relevant.

Michael Paquier, Kyotaro Horiguchi

Discussion: <20160704.160213.111134711.horiguchi.kyotaro@lab.ntt.co.jp>