Hardcode xterm as the default terminal for tests

Since the original menus were created with xterm set as the default
terminal emulator, make sure it is also used for testing as well.

tests/Makefile

@@ -11,31 +11,31 @@ test: clean generate
 
 generate:
 	mkdir -p menus_test
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f blackbox > menus_test/blackbox_en
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f fluxbox > menus_test/fluxbox_en
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f fluxbox -i > menus_test/fluxbox_icons_en
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f fluxbox -i -s 48 > menus_test/fluxbox_icons48_en
-	XDGMENUMAKER_TEST=1 LANG=el_GR.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=el_GR.utf8 \
 		$(PYTHON) $(MM) -f fluxbox > menus_test/fluxbox_el
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f fluxbox -n > menus_test/fluxbox_nosubmenu_en
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f icewm > menus_test/icewm_en
-	XDGMENUMAKER_TEST=1 LANG=de_DE.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=de_DE.utf8 \
 		$(PYTHON) $(MM) -f icewm > menus_test/icewm_de
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f jwm > menus_test/jwm_en
-	XDGMENUMAKER_TEST=1 LANG=fr_FR.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=fr_FR.utf8 \
 		$(PYTHON) $(MM) -f jwm > menus_test/jwm_fr
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f pekwm > menus_test/pekwm_en
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f pekwm --pekwm-dynamic > menus_test/pekwm_dynamic_en
-	XDGMENUMAKER_TEST=1 LANG=en_US.utf8 \
+	XDGMENUMAKER_TEST=1 XDGMENUMAKERTERM=xterm LANG=en_US.utf8 \
 		$(PYTHON) $(MM) -f windowmaker > menus_test/windowmaker_en
 
 clean: