Update -Wuninitialized to be stricter on CK_NoOp casts.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218715 91177308-0d34-0410-b5e6-96231b3b80d8
Enable both C and C++ modules with -fmodules, by switching -fcxx-modules to
being on by default. -fno-cxx-modules can still be used to enable C modules but
not C++ modules, but C++ modules is not significantly less stable than C
modules any more.

Also remove some of the scare words from the modules documentation. We're
certainly not going to remove modules support (though we might change the
interface), and it works well enough to bootstrap and build lots of
non-trivial code.

Note that this does not represent a commitment to the current interface nor
implementation, and we still intend to follow whatever direction the C and C++
committees take regarding modules support.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218717 91177308-0d34-0410-b5e6-96231b3b80d8
Update uninitialized tests to ensure that field initialization has the
same coverage as the global checker.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218720 91177308-0d34-0410-b5e6-96231b3b80d8