package/dropbear: bump version to 2019.77

package/dropbear: bump version to 2019.77

Drop patches as they are now upstream.  Add a hash for the license file.

Verified that runtime test still works:

./support/testing/run-tests -o tests.package.test_dropbear
20:42:44 TestDropbear                             Starting
20:42:45 TestDropbear                             Building
20:44:18 TestDropbear                             Building done
20:44:24 TestDropbear                             Cleaning up
.
----------------------------------------------------------------------
Ran 1 test in 100.727s

OK

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>