Minor bugfix: Add a NULL check for dh
Dereference before null check: fixed
Logically dead code: fixed
Missing break in switch: commented
surround macros with braces

fixes unintended use in special cases
Unchecked return value: fixed
use dedicated coverity_scan branch
added Coverity Scan Badge
fixed missing semi colon

regression from e4849bf77a9e6fa633a6546e0bf8a37e70462f0b
Dereference null return value: fixed
Replace our consttime_memcmp with OpenSSLs builtin CRYPTO_memcmp

CRYPTO_memcmp is also constant time (as opposed to OPENSSL_memcmp).
Furthermore our consttime_memcmp was buggy.
Merge remote-tracking branch 'upstream/master'