WRaster: Add initialisation for locale support

Because the library does not have an initialisation function, we need to
rely on an automatic called-on-load mechanism, which is provided through
a compiler attribute 'constructor'.

However, as the project aims to still compile on old hard/software, we
include a check in 'configure' to ensure it works, and if not use the
legacy solution.

Note: Because we introduce a new DEFINE, the 'config.h.in' needs to be
regenerated, otherwise you may get a compilation error in wrlib. This is
done by re-running './autogen.sh'

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

wrlib/misc.c

@@ -245,6 +245,27 @@ const char *RMessageForError(int errorCode)
 	}
 }
 
+#ifdef I18N
+/*
+ * Setup internationalization on startup
+ *
+ * For historical reason, the WRaster library does not have a function that
+ * user is supposed to call to initialise the library. Because we need to do
+ * some stuff now, we rely on the compiler attribute to tell this function
+ * has to be called automatically when library is loaded.
+ */
+void WLIB_CONSTRUCTOR(RStartup) (void)
+{
+	const char *locale_path;
+
+	locale_path = getenv("NLSPATH");
+	if (locale_path == NULL)
+		locale_path = LOCALEDIR;
+
+	bindtextdomain("WRaster", locale_path);
+}
+#endif
+
 /*
  * cleaning third-party libs at shutdown
  */