config.mak.uname: correct perl path on FreeBSD

It looks the the symlink /usr/bin/perl (to /usr/local/bin/perl) has
been removed at least on FreeBSD 10.3. See [1] for more information.

[1] https://svnweb.freebsd.org/ports/head/UPDATING?r1=386270&r2=386269&pathrev=386270&diff_format=c

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Helped-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.mak.uname

@@ -203,6 +203,7 @@ ifeq ($(uname_S),FreeBSD)
 		NO_STRTOUMAX = YesPlease
 	endif
 	PYTHON_PATH = /usr/local/bin/python
+	PERL_PATH = /usr/local/bin/perl
 	HAVE_PATHS_H = YesPlease
 	GMTIME_UNRELIABLE_ERRORS = UnfortunatelyYes
 	HAVE_BSD_SYSCTL = YesPlease