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

fusl/src/time/__tm_to_secs.c

Index: fusl/src/time/__tm_to_secs.c
diff --git a/fusl/src/time/__tm_to_secs.c b/fusl/src/time/__tm_to_secs.c
new file mode 100644
index 0000000000000000000000000000000000000000..c29fa985a6dd58fdffa9190e995d993b9e4c4427
--- /dev/null
+++ b/fusl/src/time/__tm_to_secs.c
@@ -0,0 +1,24 @@
+#include "time_impl.h"
+
+long long __tm_to_secs(const struct tm *tm)
+{
+	int is_leap;
+	long long year = tm->tm_year;
+	int month = tm->tm_mon;
+	if (month >= 12 || month < 0) {
+		int adj = month / 12;
+		month %= 12;
+		if (month < 0) {
+			adj--;
+			month += 12;
+		}
+		year += adj;
+	}
+	long long t = __year_to_secs(year, &is_leap);
+	t += __month_to_secs(month, is_leap);
+	t += 86400LL * (tm->tm_mday-1);
+	t += 3600LL * tm->tm_hour;
+	t += 60LL * tm->tm_min;
+	t += tm->tm_sec;
+	return t;
+}