Don't cache DESTDIR in perl/perl.mak.

DESTDIR is supposed to be overridden on 'make install' after doing
'make'.  Have the automatically generated perl/perl.mak not cache the
value of DESTDIR to support that for the perl/ subdirectory also.
Signed-off-by: NGerrit Pape <pape@smarden.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Makefile

@@ -1025,7 +1025,7 @@ install: all
 	$(INSTALL) $(ALL_PROGRAMS) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(INSTALL) git$X '$(DESTDIR_SQ)$(bindir_SQ)'
 	$(MAKE) -C templates DESTDIR='$(DESTDIR_SQ)' install
-	$(MAKE) -C perl prefix='$(prefix_SQ)' install
+	$(MAKE) -C perl prefix='$(prefix_SQ)' DESTDIR='$(DESTDIR_SQ)' install
 ifndef NO_TCLTK
 	$(MAKE) -C gitk-git install
 	$(MAKE) -C git-gui install

perl/Makefile.PL

@@ -17,9 +17,6 @@ if ($@ || $Error::VERSION < 0.15009) {
 	$pm{'private-Error.pm'} = '$(INST_LIBDIR)/Error.pm';
 }
 
-my %extra;
-$extra{DESTDIR} = $ENV{DESTDIR} if $ENV{DESTDIR};
-
 # redirect stdout, otherwise the message "Writing perl.mak for Git"
 # disrupts the output for the target 'instlibdir'
 open STDOUT, ">&STDERR";
@@ -29,6 +26,5 @@ WriteMakefile(
 	VERSION_FROM    => 'Git.pm',
 	PM		=> \%pm,
 	MAKEFILE	=> 'perl.mak',
-	INSTALLSITEMAN3DIR => '$(SITEPREFIX)/share/man/man3',
-	%extra
+	INSTALLSITEMAN3DIR => '$(SITEPREFIX)/share/man/man3'
 );