Use perl for version number replacement.

This patch changes Makefile to use perl for version number replacement to fix
'make install' on Darwin. The problem is that GNU sed and sed on Darwin (and
probably on BSDs) behave differently with regards to the '-i' command line
option.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Heikki Hokkanen <hoxu@users.sf.net>

Makefile

@@ -4,7 +4,7 @@ RESOURCEDIR=$(PREFIX)/share/gitstats
 RESOURCES=gitstats.css sortable.js *.gif
 BINARIES=gitstats
 VERSION=$(shell git describe 2>/dev/null || git rev-parse --short HEAD)
-SEDVERSION=sed -i 's/VERSION = 0/VERSION = "$(VERSION)"/'
+SEDVERSION=perl -pi -e 's/VERSION = 0/VERSION = "$(VERSION)"/' --
 
 all: help