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

fusl/src/passwd/fgetpwent.c

Index: fusl/src/passwd/fgetpwent.c
diff --git a/fusl/src/passwd/fgetpwent.c b/fusl/src/passwd/fgetpwent.c
new file mode 100644
index 0000000000000000000000000000000000000000..fd472a07add9ff085d5728f887e06c24ad0ed3b1
--- /dev/null
+++ b/fusl/src/passwd/fgetpwent.c
@@ -0,0 +1,12 @@
+#define _GNU_SOURCE
+#include "pwf.h"
+
+struct passwd *fgetpwent(FILE *f)
+{
+	static char *line;
+	static struct passwd pw;
+	size_t size=0;
+	struct passwd *res;
+	__getpwent_a(f, &pw, &line, &size, &res);
+	return res;
+}