Make LLDB compile on Windows after the reformat.

Most of these issues arose as a result of header re-ordering, but
it turned up a real bug, which is that MSVC doesn't support
__attribute__((packed)) or __attribute__((aligned)).  This was
working before because there's a Windows header that #defines
__attribute__(x) to nothing.  We should fix this by removing
that #define entirely, and dealing with the fallout separately
which may turn up even more bugs.

I fixed this by replacing them with the corresponding LLVM
macros which understand how to do these operations on all the
different compilers.

llvm-svn: 280757