Don't use install(1) during build.

Make the timestamp not depend on $(DESKTOP_I18N_LOCALE_DIR) to prevent
extra recursion during install.

Index: gschem/po/Makefile.in.in
--- gschem/po/Makefile.in.in.orig
+++ gschem/po/Makefile.in.in
@@ -504,12 +504,18 @@ DESKTOP_I18N_LOCALE_DIR = @DESKTOP_I18N_LOCALE_DIR@
 # the timestamp before *and* after running 'make install' so that the
 # make doesn't go into an infinite loop!
 all: stamp-i18n
-stamp-i18n: $(DESKTOP_I18N_LOCALE_DIR) stamp-po Makefile
+stamp-i18n: stamp-po Makefile
+	$(MKDIR_P) $(DESKTOP_I18N_LOCALE_DIR)
 	@echo timestamp > stamp-i18nT && mv -f stamp-i18nT stamp-i18n
-	$(MAKE) 	  prefix=$(DESKTOP_I18N_LOCALE_DIR) 	  localedir=$(DESKTOP_I18N_LOCALE_DIR)/share/locale 	  DESTDIR= install && 	cp $(srcdir)/LINGUAS $(DESKTOP_I18N_LOCALE_DIR)/$(DOMAIN).LINGUAS 	|| rm stamp-i18n
+	$(MAKE) \
+	    prefix=$(DESKTOP_I18N_LOCALE_DIR) \
+	    localedir=$(DESKTOP_I18N_LOCALE_DIR)/share/locale \
+	    DESTDIR= \
+	    INSTALL_DATA=cp \
+	    install \
+	&& cp $(srcdir)/LINGUAS $(DESKTOP_I18N_LOCALE_DIR)/$(DOMAIN).LINGUAS \
+	|| rm stamp-i18n
 	@echo timestamp > stamp-i18nT && mv -f stamp-i18nT stamp-i18n
-$(DESKTOP_I18N_LOCALE_DIR):
-	$(MKDIR_P) $(DESKTOP_I18N_LOCALE_DIR)
 
 clean: clean-i18n
 clean-i18n: