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

fusl/src/stdio/fclose.c

+#include "stdio_impl.h"
+#include "libc.h"
+
+static void dummy(FILE *f) { }
+weak_alias(dummy, __unlist_locked_file);
+
+int fclose(FILE *f)
+{
+        int r;
+        int perm;
+        
+        FLOCK(f);
+
+        __unlist_locked_file(f);
+
+        if (!(perm = f->flags & F_PERM)) {
+                FILE **head = __ofl_lock();
+                if (f->prev) f->prev->next = f->next;
+                if (f->next) f->next->prev = f->prev;
+                if (*head == f) *head = f->next;
+                __ofl_unlock();
+        }
+
+        r = fflush(f);
+        r |= f->close(f);
+
+        if (f->getln_buf) free(f->getln_buf);
+        if (!perm) free(f);
+        else FUNLOCK(f);
+
+        return r;
+}