i18n: Make VGETTEXT()/VNGETTEXT() always require a GETTEXT_DOMAIN to …

…be defined

This drops a preprocessor conditional branch that is dead code now that
the file pulls gettext.hpp and the GETTEXT_DOMAIN defaults with it.

See also PR #2711.

(cherry-picked from commit a602391)

src/formula/string_utils.hpp

@@ -94,10 +94,5 @@ std::string vngettext(const char*, const char*, const char*, int, const utils::s
  * the function.
  */
 
-#ifdef GETTEXT_DOMAIN
 #define	VGETTEXT(msgid, ...) vgettext(GETTEXT_DOMAIN, msgid, __VA_ARGS__)
 #define	VNGETTEXT(msgid, msgid_plural, count, ...) vngettext(GETTEXT_DOMAIN, msgid, msgid_plural, count, __VA_ARGS__)
-#else
-#define	VGETTEXT(msgid, ...) vgettext(msgid, __VA_ARGS__)
-#define	VNGETTEXT(msgid, msgid_plural, count, ...) vngettext(msgid, msgid_plural, count, __VA_ARGS__)
-#endif