Introduce -fsanitize-coverage=N flag

Summary:
This change makes the asan-coverge (formerly -mllvm -asan-coverge)
accessible via a clang flag.
Companion patch to LLVM is http://reviews.llvm.org/D6152

Test Plan: regression tests, chromium

Reviewers: samsonov

Reviewed By: samsonov

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D6153

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221719 91177308-0d34-0410-b5e6-96231b3b80d8
Fix some formatting prior to refactoring the code.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221722 91177308-0d34-0410-b5e6-96231b3b80d8
Explicitly exclude keywords from the member validator.

Also simply and remove dead code from MemberExprTypoRecovery.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221723 91177308-0d34-0410-b5e6-96231b3b80d8
Make LookupResult be copyable to avoid decomposing an existing one and
initializing a new one every time a copy is needed.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221724 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format: Improve handling of comments in binary expressions.

Before:
  b = a &&
      // Comment
      b.c &&
      d;

After:
  b = a &&
      // Comment
      b.c && d;

This fixes llvm.org/PR21535.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221727 91177308-0d34-0410-b5e6-96231b3b80d8