Makefile: help macOS novices by mentioning MacPorts

Since Aug 2006, the DarwinPorts project renamed themselves as
MacPorts.  Those who are not intimately familiar with the Opensource
ecosystem around macOS from olden days, the name DarwinPorts may not
ring a bell, even when they are using MacPorts.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reviewed-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: gitster

Makefile

@@ -95,7 +95,8 @@ include shared.mak
 # and LDFLAGS appropriately.
 #
 # Define NO_DARWIN_PORTS if you are building on Darwin/Mac OS X,
-# have DarwinPorts installed in /opt/local, but don't want GIT to
+# have DarwinPorts (which is an old name for MacPorts) installed
+# in /opt/local, but don't want GIT to
 # link against any libraries installed there.  If defined you may
 # specify your own (or DarwinPort's) include directories and
 # library directories by defining CFLAGS and LDFLAGS appropriately.