pg_controldata: Add common gettext flags

So it picks up strings in pg_log_* calls.  This was forgotten when it
was added to all other relevant subdirectories.

src/bin/pg_controldata/nls.mk

@@ -2,3 +2,5 @@
 CATALOG_NAME     = pg_controldata
 AVAIL_LANGUAGES  = cs de es fr it ja ko pl pt_BR ru sv tr vi zh_CN
 GETTEXT_FILES    = pg_controldata.c ../../common/controldata_utils.c
+GETTEXT_TRIGGERS = $(FRONTEND_COMMON_GETTEXT_TRIGGERS)
+GETTEXT_FLAGS    = $(FRONTEND_COMMON_GETTEXT_FLAGS)