Use double quotes for nmake [ci skip]

common.mk

@@ -1404,12 +1404,12 @@ extract-gems: outdate-bundled-gems
 outdate-bundled-gems: PHONY
 	$(Q) $(BASERUBY) -C "$(srcdir)" \
 	-rfileutils \
-	-e 'Dir.glob(".bundle/gems/*/") {|g|' \
-	-e   'FileUtils::Verbose.rm_rf(g) unless File.exist?("gems/#{File.basename(g)}.gem")' \
-	-e '}' \
-	-e 'Dir.glob(".bundle/specifications/*.gemspec") {|g|' \
-	-e   'FileUtils::Verbose.rm_f(g) unless File.exist?("gems/#{File.basename(g, ".gemspec")}.gem")' \
-	-e '}'
+	-e "Dir.glob('.bundle/gems/*/') {|g|" \
+	-e   "FileUtils::Verbose.rm_rf(g) unless File.exist?(%[gems/#{File.basename(g)}.gem])" \
+	-e "}" \
+	-e "Dir.glob('.bundle/specifications/*.gemspec') {|g|" \
+	-e   "FileUtils::Verbose.rm_f(g) unless File.exist?(%[gems/#{File.basename(g, '.gemspec')}.gem])" \
+	-e "}"
 
 update-bundled_gems: PHONY
 	$(Q) $(RUNRUBY) -rrubygems \