Use make functions for HELP_LINGUAS

Author: rbuj

help/Makefile.am

@@ -29,7 +29,11 @@ HELP_FILES = absolute.page \
              trigonometry.page \
              variables.page
 
-HELP_LINGUAS = bg ca cs de el es eu fi fr gl hu it ja ko lv oc pt_BR ro ru sl sv te zh_CN zh_HK zh_TW
+# Add linguas to be ignored, e.g. IGNORE_HELP_LINGUAS = ca de es fr
+IGNORE_HELP_LINGUAS =
+HELP_LINGUAS = $(if $(IGNORE_HELP_LINGUAS), \
+	$(filter-out $(IGNORE_HELP_LINGUAS),$(subst /,,$(dir $(wildcard */*.po)))), \
+	$(subst /,,$(dir $(wildcard */*.po))) )
 
 DISTCLEANFILES = \
 	Makefile.in