Add gettext support

configure.ac

@@ -73,6 +73,7 @@ AS_IF([test -z "$INTLTOOL_POLICY_RULE"], [
 
 GETTEXT_PACKAGE=systemd
 AC_SUBST(GETTEXT_PACKAGE)
+AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE, "$GETTEXT_PACKAGE", [systemd])
 
 AC_PROG_MKDIR_P
 AC_PROG_LN_S

src/shared/util.c

@@ -25,6 +25,8 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <signal.h>
+#include <libintl.h>
+#include <locale.h>
 #include <stdio.h>
 #include <syslog.h>
 #include <sched.h>
@@ -74,6 +76,7 @@
 #include <sys/auxv.h>
 #endif
 
+#include "config.h"
 #include "macro.h"
 #include "util.h"
 #include "ioprio.h"
@@ -5782,6 +5785,11 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
         return NULL;
 }
 
+void init_gettext(void) {
+        setlocale(LC_ALL, "");
+        textdomain(GETTEXT_PACKAGE);
+}
+
 bool is_locale_utf8(void) {
         const char *set;
         static int cached_answer = -1;

src/shared/util.h

@@ -737,6 +737,8 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
                  int (*compar) (const void *, const void *, void *),
                  void *arg);
 
+#define _(String) gettext (String)
+void init_gettext(void);
 bool is_locale_utf8(void);
 
 typedef enum DrawSpecialChar {