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

fusl/src/ipc/shmat.c

Index: fusl/src/ipc/shmat.c
diff --git a/fusl/src/ipc/shmat.c b/fusl/src/ipc/shmat.c
new file mode 100644
index 0000000000000000000000000000000000000000..38db92f9511486fa5ff69001040678e45579e2d3
--- /dev/null
+++ b/fusl/src/ipc/shmat.c
@@ -0,0 +1,17 @@
+#include <sys/shm.h>
+#include "syscall.h"
+#include "ipc.h"
+
+#ifdef SYS_shmat
+void *shmat(int id, const void *addr, int flag)
+{
+	return (void *)syscall(SYS_shmat, id, addr, flag);
+}
+#else
+void *shmat(int id, const void *addr, int flag)
+{
+	unsigned long ret;
+	ret = syscall(SYS_ipc, IPCOP_shmat, id, flag, &addr, addr);
+	return (ret > -(unsigned long)SHMLBA) ? (void *)ret : (void *)addr;
+}
+#endif