Move CodeGenFileType enum to Support/CodeGen.h

Avoids the need to include TargetMachine.h from various places just for
an enum. Various other enums live here, such as the optimization level,
TLS model, etc. Data suggests that this change probably doesn't matter,
but it seems nice to have anyway.

GitOrigin-RevId: 1dfede3122eec83b885d788553e3620806d54650
1 file changed