Prior to this change, BoringSSL maintained a 2-byte buffer for alerts,
and would support reassembly of fragmented alerts.
NSS does not support fragmented alerts, nor would any reasonable
implementation produce them. Remove fragmented alert handling and
produce an error if a fragmented alert has ever been encountered.
Change-Id: I31530ac372e8a90b47cf89404630c1c207cfb048
Reviewed-on: https://boringssl-review.googlesource.com/2125
Reviewed-by: Adam Langley <agl@google.com>
4cd8c43e73