locale-util: drop libintl dependency

Both glibc and musl provides dgettext(). Hence it is not necessary to
use libintl.so provided by gettext.

This partially reverts 590e226437,
fully reverts commit e6e65dc261 and
bd19ffd9cb.

Then, introduce minimal libintl.h for musl build, to avoid using
libintl.h by gettext, which is typically installed on musl-based
build systems.

src/basic/locale-util.c

@@ -7,12 +7,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-#ifndef __GLIBC__
-#include "sd-dlopen.h"
-#endif
-
 #include "dirent-util.h"
-#include "dlfcn-util.h"
 #include "env-util.h"
 #include "fd-util.h"
 #include "fileio.h"
@@ -27,28 +22,6 @@
 #include "strv.h"
 #include "utf8.h"
 
-#ifdef __GLIBC__
-DLSYM_PROTOTYPE(dgettext) = dgettext;
-#else
-DLSYM_PROTOTYPE(dgettext) = NULL;
-#endif
-
-int dlopen_libintl(int log_level) {
-#ifdef __GLIBC__
-        return 1;
-#else
-        static void *libintl_dl = NULL;
-
-        LIBINTL_NOTE(SD_ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED);
-
-        return dlopen_many_sym_or_warn(
-                        &libintl_dl,
-                        "libintl.so.8",
-                        log_level,
-                        DLSYM_ARG(dgettext));
-#endif
-}
-
 static char* normalize_locale(const char *name) {
         const char *e;
 

src/basic/locale-util.h

@@ -4,33 +4,7 @@
 #include <libintl.h>    /* IWYU pragma: export */
 #include <locale.h>     /* IWYU pragma: export */
 
-#include "sd-dlopen.h"  /* IWYU pragma: export */
-
 #include "basic-forward.h"
-#include "dlfcn-util.h"
-
-/* format_arg(2) propagates the format-string nature of the second argument to the return value, so that
- * printf(_("Hello %s"), name) still gets checked. It survives both DLSYM_PROTOTYPE's typeof() and the
- * ternary in _() below — verified on gcc and clang. */
-extern DLSYM_PROTOTYPE(dgettext) __attribute__((format_arg(2)));
-
-int dlopen_libintl(int log_level);
-
-#ifdef __GLIBC__
-#define DLOPEN_LIBINTL(log_level, priority) dlopen_libintl(log_level)
-#else
-#define LIBINTL_NOTE(priority)                                          \
-        SD_ELF_NOTE_DLOPEN("intl",                                      \
-                           "Support for message translation via gettext", \
-                           priority,                                    \
-                           "libintl.so.8")
-
-#define DLOPEN_LIBINTL(log_level, priority)                             \
-        ({                                                              \
-                LIBINTL_NOTE(priority);                                 \
-                dlopen_libintl(log_level);                              \
-        })
-#endif
 
 typedef enum LocaleVariable {
         /* We don't list LC_ALL here on purpose. People should be
@@ -58,9 +32,7 @@ int get_locales(char ***ret);
 bool locale_is_valid(const char *name);
 int locale_is_installed(const char *name);
 
-/* Falls back to the untranslated string if dlopen_libintl() hasn't run or has failed, so callers don't have
- * to gate every translatable message on a runtime check. */
-#define _(String) (sym_dgettext ? sym_dgettext(GETTEXT_PACKAGE, (String)) : (String))
+#define _(String) dgettext(GETTEXT_PACKAGE, String)
 #define N_(String) String
 
 bool is_locale_utf8(void);