Reorganize #includes to follow LLVM Coding Standards.
Include some missing headers. Required to use `Printf()`.
Aside from that, this patch contains no functional change.
It is purely a re-organization.
Differential Revision: https://reviews.llvm.org/D27363
llvm-svn: 289560
Windows doesn't really support weak aliases, but with some
linker magic we can get something that's pretty close on
Windows. This introduces an interface to accessing weakly
aliased symbols that will work on any platform. Linker
magic changes to come in a separate patch.
Patch by Marcos Pividori
Differential Revision: https://reviews.llvm.org/D27235
llvm-svn: 288530