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

fusl/src/stdio/fflush.c

Index: fusl/src/stdio/fflush.c
diff --git a/fusl/src/stdio/fflush.c b/fusl/src/stdio/fflush.c
new file mode 100644
index 0000000000000000000000000000000000000000..3f462c80e8d12f6efbecd144a144d430736ec6eb
--- /dev/null
+++ b/fusl/src/stdio/fflush.c
@@ -0,0 +1,48 @@
+#include "stdio_impl.h"
+
+static int __fflush_unlocked(FILE *f)
+{
+	/* If writing, flush output */
+	if (f->wpos > f->wbase) {
+		f->write(f, 0, 0);
+		if (!f->wpos) return EOF;
+	}
+
+	/* If reading, sync position, per POSIX */
+	if (f->rpos < f->rend) f->seek(f, f->rpos-f->rend, SEEK_CUR);
+
+	/* Clear read and write modes */
+	f->wpos = f->wbase = f->wend = 0;
+	f->rpos = f->rend = 0;
+
+	return 0;
+}
+
+/* stdout.c will override this if linked */
+static FILE *volatile dummy = 0;
+weak_alias(dummy, __stdout_used);
+
+int fflush(FILE *f)
+{
+	int r;
+
+	if (f) {
+		FLOCK(f);
+		r = __fflush_unlocked(f);
+		FUNLOCK(f);
+		return r;
+	}
+
+	r = __stdout_used ? fflush(__stdout_used) : 0;
+
+	for (f=*__ofl_lock(); f; f=f->next) {
+		FLOCK(f);
+		if (f->wpos > f->wbase) r |= __fflush_unlocked(f);
+		FUNLOCK(f);
+	}
+	__ofl_unlock();
+	
+	return r;
+}
+
+weak_alias(__fflush_unlocked, fflush_unlocked);