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

fusl/src/unistd/getcwd.c

Index: fusl/src/unistd/getcwd.c
diff --git a/fusl/src/unistd/getcwd.c b/fusl/src/unistd/getcwd.c
new file mode 100644
index 0000000000000000000000000000000000000000..a7b925d2dbee5a99f5ec61b77b5870ae3a839143
--- /dev/null
+++ b/fusl/src/unistd/getcwd.c
@@ -0,0 +1,19 @@
+#include <unistd.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#include "syscall.h"
+
+char *getcwd(char *buf, size_t size)
+{
+	char tmp[PATH_MAX];
+	if (!buf) {
+		buf = tmp;
+		size = PATH_MAX;
+	} else if (!size) {
+		errno = EINVAL;
+		return 0;
+	}
+	if (syscall(SYS_getcwd, buf, size) < 0) return 0;
+	return buf == tmp ? strdup(buf) : buf;
+}