add obsolete futimesat()

this function is obsolete, however it's available as a syscall
and as such qemu userspace emulation tries to forward it to the
host kernel.

include/sys/time.h

@@ -31,6 +31,7 @@ int utimes (const char *, const struct timeval [2]);
 
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
 int futimes(int, const struct timeval [2]);
+int futimesat(int, const char *, const struct timeval [2]);
 int lutimes(const char *, const struct timeval [2]);
 int settimeofday (const struct timeval *, void *);
 int adjtime (const struct timeval *, struct timeval *);

src/stat/futimesat.c

+#include <sys/time.h>
+#include "syscall.h"
+
+#ifdef SYS_futimesat
+int futimesat(int dirfd, const char *pathname, const struct timeval times[2])
+{
+	return syscall(SYS_futimesat, dirfd, pathname, times);
+}
+#endif