Options.td: O0 and O4 are not Joined options

(I'm not sure how to test this because the Driver will still accept
 e.g. "-O4foo", but it goes in the catch-all -O option instead of -O4.)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187602 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: Emit template arguments for limited types used for context.

We emit definitions with no members when a nested type is
referenced/required (GCC does the same, to be fair) but failed to attach
the template arguments in such a case.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187608 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: Don't prefer declarations over definitions in -flimit-debug-info in C

Without an ODR, the -flimit-debug-info debug info size optimization of
emitting declarations for fully defined types when only a declaration is
needed by the TU, is incorrect. Emit the full definition whenever it's
available in non-C++.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187611 91177308-0d34-0410-b5e6-96231b3b80d8
Use function attributes to indicate if we don't want to realign the stack.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187617 91177308-0d34-0410-b5e6-96231b3b80d8
Use llvm::sys::fs::UniqueID for windows and unix.

This unifies the unix and windows versions of FileManager::UniqueDirContainer
and FileManager::UniqueFileContainer by using UniqueID.

We cannot just replace "struct stat" with llvm::sys::fs::file_status, since we
want to be able to construct fake ones, and file_status has different members
on unix and windows.

What the patch does is:

* Record only the information that clang is actually using.
* Use llvm::sys::fs::status instead of stat and fstat.
* Use llvm::sys::fs::UniqueID
* Delete the old windows versions of UniqueDirContainer and
UniqueFileContainer since the "unix" one now works on windows too.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187619 91177308-0d34-0410-b5e6-96231b3b80d8