Add a "fork" of musl as //fusl.

fusl/src/internal/locale_impl.h

+#ifndef _LOCALE_IMPL_H
+#define _LOCALE_IMPL_H
+
+#include <locale.h>
+#include <stdlib.h>
+#include "libc.h"
+#include "pthread_impl.h"
+
+#define LOCALE_NAME_MAX 15
+
+struct __locale_map {
+        const void *map;
+        size_t map_size;
+        char name[LOCALE_NAME_MAX+1];
+        const struct __locale_map *next;
+};
+
+extern const struct __locale_map __c_dot_utf8;
+extern const struct __locale_struct __c_locale;
+extern const struct __locale_struct __c_dot_utf8_locale;
+
+const struct __locale_map *__get_locale(int, const char *);
+const char *__mo_lookup(const void *, size_t, const char *);
+const char *__lctrans(const char *, const struct __locale_map *);
+const char *__lctrans_cur(const char *);
+
+#define LCTRANS(msg, lc, loc) __lctrans(msg, (loc)->cat[(lc)])
+#define LCTRANS_CUR(msg) __lctrans_cur(msg)
+
+#define C_LOCALE ((locale_t)&__c_locale)
+#define UTF8_LOCALE ((locale_t)&__c_dot_utf8_locale)
+
+#define CURRENT_LOCALE (__pthread_self()->locale)
+
+#define CURRENT_UTF8 (!!__pthread_self()->locale->cat[LC_CTYPE])
+
+#undef MB_CUR_MAX
+#define MB_CUR_MAX (CURRENT_UTF8 ? 4 : 1)
+
+#endif