configure: update .h for clock_adjtime

man clock_adjtime: #include <sys/timex.h>
for glibc, if _GNU_SOURCE is defined, <time.h> will include <sys/timex.h>
but not for musl, so replce <time.h> to <sys/timex.h>

PS it seems clock_adjtime is used nowhere?

Signed-off-by: Z. Liu <zhixu.liu@gmail.com>

qemu/configure

@@ -1454,7 +1454,7 @@ fi
 # clock_adjtime probe
 clock_adjtime=no
 cat > $TMPC <<EOF
-#include <time.h>
+#include <sys/timex.h>
 
 int main(void)
 {