Run clang-tidy modernize-use-equals-{delete,default} on //crypto

See the bugs and cxx post for justification and details:
https://groups.google.com/a/chromium.org/forum/#!topic/cxx/RkOHzIK6Tq8

This change was done using clang-tidy as described here:
https://chromium.googlesource.com/chromium/src/+/lkcr/docs/clang_tidy.md

In some cases the the tool leaves behind a string of commas where it
replaced a member initializer list
(https://bugs.llvm.org/show_bug.cgi?id=35051). They were cleaned up with:
  git diff --name-only | \
    xargs sed -E -i 's/(^\s*|\)\s*):[ ,]*= default/\1 = default/'

BUG=778959,778957

Change-Id: Ie37f2c19a84ecdce173b34b27a0a63c187b3f54a
Reviewed-on: https://chromium-review.googlesource.com/789740
Reviewed-by: David Benjamin <[email protected]>
Commit-Queue: Chris Watkins <[email protected]>
Cr-Commit-Position: refs/heads/master@{#520426}
diff --git a/crypto/aead.cc b/crypto/aead.cc
index 99d1603..83187ba7 100644
--- a/crypto/aead.cc
+++ b/crypto/aead.cc
@@ -24,8 +24,7 @@
   }
 }
 
-Aead::~Aead() {
-}
+Aead::~Aead() = default;
 
 void Aead::Init(const std::string* key) {
   DCHECK(!key_);