Tidy up dtls1_hm_fragment_new and fix (unreachable) memory leak.

clang scan-build found a memory leak if the overflow codepath in
dtls1_hm_fragment is hit. Along the way, tidy up that function.

Change-Id: I3c4b88916ee56ab3ab63f93d4a967ceae381d187
Reviewed-on: https://boringssl-review.googlesource.com/5870
Reviewed-by: Adam Langley <agl@google.com>
1 file changed