i18n: Remove no-op translation::init() function

This function only ever had an implementation when building the i18n API
to use libintl instead of Boost.Locale was possible, in which case its
implementation would be a std::setlocale() call specific to POSIX
systems.

I'm not backporting this to 1.14 since it's an inconsequential cosmetic
thing, or so I'd like to think. Last time someone tried to remove a
similarly empty "init" function elsewhere, things went south pretty
quickly.

src/gettext.hpp

@@ -74,8 +74,6 @@ namespace translation
 
 	void set_language(const std::string& language, const std::vector<std::string>* alternates);
 
-	void init();
-
 	/** Case-sensitive lexicographical comparison. */
 	int compare(const std::string& s1,const std::string& s2);
 

src/gettext_boost.cpp

@@ -438,10 +438,6 @@ int icompare(const std::string& s1, const std::string& s2)
 #endif
 }
 
-void init()
-{
-}
-
 std::string strftime(const std::string& format, const std::tm* time)
 {
 	std::basic_ostringstream<char> dummy;

src/tests/utils/game_config_manager.cpp

@@ -63,7 +63,6 @@ namespace test_utils {
 			setlocale(LC_ALL, "English");
 #else
 			std::setlocale(LC_ALL, "C");
-			translation::init();
 #endif
 			const std::string& intl_dir = filesystem::get_intl_dir();
 			translation::bind_textdomain("wesnoth", intl_dir.c_str(), "UTF-8");

src/wesnoth.cpp

@@ -506,7 +506,6 @@ static void init_locale()
 	setlocale(LC_ALL, "English");
 #else
 	std::setlocale(LC_ALL, "C");
-	translation::init();
 #endif
 
 	const std::string& intl_dir = filesystem::get_intl_dir();