Ensure translate and check-translate use the same command

They had diverged. This doesn't appear to be the cause of the build failure
on #8614, but it doesn't hurt to make sure they always match.

Author: jepler

Makefile

@@ -226,8 +226,9 @@ pseudoxml:
 .PHONY: all-source
 all-source:
 
+TRANSLATE_COMMAND=find $(TRANSLATE_SOURCES) -type d \( $(TRANSLATE_SOURCES_EXC) \) -prune -o -type f \( -iname "*.c" -o -iname "*.h" \) -print | (LC_ALL=C sort) | xgettext -x locale/synthetic.po -f- -L C -s --add-location=file --keyword=MP_ERROR_TEXT -o - | sed -e '/"POT-Creation-Date: /d'
 locale/circuitpython.pot: all-source
-	find $(TRANSLATE_SOURCES) -type d \( $(TRANSLATE_SOURCES_EXC) \) -prune -o -type f \( -iname "*.c" -o -iname "*.h" \) -print | (LC_ALL=C sort) | xgettext -x locale/synthetic.po -f- -L C -s --add-location=file --keyword=MP_ERROR_TEXT -o - | sed -e '/"POT-Creation-Date: /d' > $@
+	$(TRANSLATE_COMMAND) > $@
 
 # Historically, `make translate` updated the .pot file and ran msgmerge.
 # However, this was a frequent source of merge conflicts.  Weblate can perform
@@ -252,7 +253,7 @@ merge-translate:
 
 .PHONY: check-translate
 check-translate:
-	find $(TRANSLATE_SOURCES) -type d \( $(TRANSLATE_SOURCES_EXC) \) -prune -o -type f \( -iname "*.c" -o -iname "*.h" \) -print | (LC_ALL=C sort) | xgettext -f- -L C -s --add-location=file --keyword=translate --keyword=MP_ERROR_TEXT -o circuitpython.pot.tmp -p locale
+	$(TRANSLATE_COMMAND) > locale/circuitpython.pot.tmp
 	$(PYTHON) tools/check_translations.py locale/circuitpython.pot.tmp locale/circuitpython.pot; status=$$?; rm -f locale/circuitpython.pot.tmp; exit $$status
 
 .PHONY: stubs