Add getloadavg for android (since api v29)

Author: coolreader18

src/unix/linux_like/android/mod.rs

@@ -2457,6 +2457,7 @@ extern "C" {
         sevlen: ::size_t,
         flags: ::c_int,
     ) -> ::c_int;
+    pub fn getloadavg(loadavg: *mut ::c_double, nelem: ::c_int) -> ::c_int;
     pub fn preadv(fd: ::c_int, iov: *const ::iovec, count: ::c_int, offset: ::off_t) -> ::ssize_t;
     pub fn pwritev(fd: ::c_int, iov: *const ::iovec, count: ::c_int, offset: ::off_t) -> ::ssize_t;
     pub fn process_vm_readv(