RT 3493: fix RSA test

- Pass in the right ciphertext length to ensure we're indeed testing
  ciphertext corruption (and not truncation).
- Only test one mutation per byte to not make the test too slow.
- Add a separate test for truncated ciphertexts.

(Imported from upstream's 5f623eb61655688501cb1817a7ad0592299d894a.)

Change-Id: I425a77668beac9d391387e3afad8d15ae387468f
Reviewed-on: https://boringssl-review.googlesource.com/5945
Reviewed-by: Adam Langley <agl@google.com>
1 file changed