i18n: get translation entries for description of each compression engines

Now, hggettext can be applied safely on util.py, of which
i18nfunctions contains appropriate objects related to each compression
types.

Makefile

@@ -132,6 +132,7 b' i18n/hg.pot: $(PYFILES) $(DOCFILES) i18n'
 	  mercurial/templater.py \
 	  mercurial/filemerge.py \
 	  mercurial/hgweb/webcommands.py \
+	  mercurial/util.py \
 	  $(DOCFILES) > i18n/hg.pot.tmp
         # All strings marked for translation in Mercurial contain
         # ASCII characters only. But some files contain string

mercurial/util.py

@@ -3759,5 +3759,7 b' def bundlecompressiontopics():'
 
     return items
 
+i18nfunctions = bundlecompressiontopics().values()
+
 # convenient shortcut
 dst = debugstacktrace