tests: enclose $PERL_PATH in double quotes

Otherwise it will be split at a space after "Program" when it is set
to "\\Program Files\perl" or something silly like that.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5532-fetch-proxy.sh

@@ -15,7 +15,7 @@ test_expect_success 'setup remote repo' '
 cat >proxy <<'EOF'
 #!/bin/sh
 echo >&2 "proxying for $*"
-cmd=`$PERL_PATH -e '
+cmd=`"$PERL_PATH" -e '
 	read(STDIN, $buf, 4);
 	my $n = hex($buf) - 4;
 	read(STDIN, $buf, $n);