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

fusl/src/sched/sched_cpucount.c

Index: fusl/src/sched/sched_cpucount.c
diff --git a/fusl/src/sched/sched_cpucount.c b/fusl/src/sched/sched_cpucount.c
new file mode 100644
index 0000000000000000000000000000000000000000..94aa259e6ad5ed163038bb67b3de25e69f93a9ac
--- /dev/null
+++ b/fusl/src/sched/sched_cpucount.c
@@ -0,0 +1,11 @@
+#define _GNU_SOURCE
+#include <sched.h>
+
+int __sched_cpucount(size_t size, const cpu_set_t *set)
+{
+	size_t i, j, cnt=0;
+	const unsigned char *p = (const void *)set;
+	for (i=0; i<size; i++) for (j=0; j<8; j++)
+		if (p[i] & (1<<j)) cnt++;
+	return cnt;
+}