-fms-extensions: Recognize _alloca as an alias for the alloca builtin

Differential Revision: http://llvm-reviews.chandlerc.com/D1989

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194617 91177308-0d34-0410-b5e6-96231b3b80d8
Don't use alias from derived dtor to base dtor at -O0.

This patch disables aliasing (and rauw) of derived dtors to base dtors at -O0.
This optimization can have a negative impact on the debug quality.

This was a latent bug for some time with local classes, but got noticed when it
was generalized and broke gdb's destrprint.exp.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194618 91177308-0d34-0410-b5e6-96231b3b80d8
[objcmt] If the frontend option is frontend::MigrateSource then we don't need to create
the arcmt wrappers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194627 91177308-0d34-0410-b5e6-96231b3b80d8
[objcmt] Transfer the objcmt flags from the driver to cc1 invocation and
instantiate ObjCMigrateASTConsumer with the specific options that were enabled.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194628 91177308-0d34-0410-b5e6-96231b3b80d8
[objcmt] If no objcmt options were specified, default to enable literals+subscripting.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194629 91177308-0d34-0410-b5e6-96231b3b80d8