Comment parsing: -fparse-all-comments: recognize empty line comments

In -fparse-all-comments mode empty '//' comments were recognized as
RCK_Invalid, and were not merged with next and previous lines.

Patch by Amin Shali.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180625 91177308-0d34-0410-b5e6-96231b3b80d8
Documentation: improve description of make_shared transformation, as suggested by David Blaikie


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180627 91177308-0d34-0410-b5e6-96231b3b80d8
[driver] Implement the -fdebug-compilation-dir in a way that is compatible with
gcc.  No test case included as I'm having problems finding a test case where
the inode/dev don't match.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180628 91177308-0d34-0410-b5e6-96231b3b80d8
document parsing. When a sub-class (c++ Objective-C) missing 
a comment, grab the first comment found in its class
heirarchy. Also, when a category is mossing a comment,
grab comment of its primary class. // rdar://13647476


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180629 91177308-0d34-0410-b5e6-96231b3b80d8