git-remote-mediawiki build: handle DESTDIR/INSTLIBDIR with whitespace

Quote DESTDIR and INSTLIBDIR for the shell in the same way as is done in
the toplevel Makefile to avoid confusion in case they contain shell
metacharacters.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/mw-to-git/Makefile

@@ -16,13 +16,15 @@ INSTALL = install
 SCRIPT_PERL_FULL=$(patsubst %,$(HERE)/%,$(SCRIPT_PERL))
 INSTLIBDIR=$(shell $(MAKE) -C $(GIT_ROOT_DIR)/perl \
                 -s --no-print-directory instlibdir)
+DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
+INSTLIBDIR_SQ = $(subst ','\'',$(INSTLIBDIR))
 
 all: build
 
 install_pm:
-	$(INSTALL) -d -m 755 $(DESTDIR)$(INSTLIBDIR)/Git
+	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(INSTLIBDIR_SQ)/Git'
 	$(INSTALL) -m 644 $(GIT_MEDIAWIKI_PM) \
-		$(DESTDIR)$(INSTLIBDIR)/$(GIT_MEDIAWIKI_PM)
+		'$(DESTDIR_SQ)$(INSTLIBDIR_SQ)/$(GIT_MEDIAWIKI_PM)'
 
 build:
 	$(MAKE) -C $(GIT_ROOT_DIR) SCRIPT_PERL=$(SCRIPT_PERL_FULL) \